Betelgeuse is a
red supergiant of
spectral type
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting th ...
M1-2 and one of the
largest stars
Below are lists of the largest stars currently known, ordered by radius and separated into categories by galaxy. The unit of measurement used is the radius of the Sun (approximately ).
The angular diameters of stars can be measured directly u ...
visible to the
naked eye
Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying, light-collecting optical instrument, such as a telescope or microscope, or eye protection. Vision corrected to normal ...
. It is usually the
tenth-brightest star
A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...
in the
night sky
The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon.
Natural light sources in a night sky inc ...
and, after
Rigel
Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive componentand ...
, the second-brightest in the
constellation of
Orion. It is a distinctly reddish,
semiregular variable star whose
apparent magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...
, varying between +0.0 and +1.6, has the widest range displayed by any
first-magnitude star
First-magnitude stars are the brightest stars in the night sky, with apparent magnitudes lower (i.e. brighter) than +1.50. Hipparchus, in the 1st century B.C., introduced the magnitude scale. He allocated first magnitude to the 20 brightest stars ...
. At
near-infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
wavelengths, Betelgeuse is the brightest star in the night sky. Its
Bayer designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. T ...
is α Orionis,
Latinised to Alpha Orionis and abbreviated Alpha Ori or α Ori.
If it were at the center of our
Solar System
The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
, its surface would lie beyond the
asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...
and it would engulf the
orbit
In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such a ...
s of
Mercury,
Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...
,
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surf ...
, and
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmos ...
. Nevertheless, there are several even larger stars in the
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked ey ...
, including
supergiant
Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars s ...
s like
Mu Cephei
Mu Cephei ( Latinized from μ Cephei, abbreviated Mu Cep or μ Cep), also known as Herschel's Garnet Star, Erakis, or HD 206936, is a red supergiant or hypergiant star in the constellation Cepheus. It appears garnet red and is located a ...
and the peculiar
hypergiant
A hypergiant (luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term ''hypergiant'' is defined as luminosity class 0 (zero) in the MKK ...
,
VY Canis Majoris. Calculations of Betelgeuse's mass range from slightly under ten to a little over twenty times that of the
Sun. For
various reasons, its distance has been quite difficult to measure; current best estimates are on the order of 500–600
light-year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 101 ...
s from the Suna comparatively wide uncertainty for a relatively nearby star. Its
absolute magnitude
Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it we ...
is about −6. Less than 10 million years old, Betelgeuse has evolved rapidly because of its large mass and is expected to end its evolution with a
supernova explosion, most likely within 100,000 years. Having been ejected from its birthplace in the
Orion OB1 associationwhich includes the stars in
Orion's Belt
Orion's Belt or the Belt of Orion, also known as the Three Kings or Three Sisters, is an asterism in the constellation Orion. It consists of the three bright stars Alnitak, Alnilam and Mintaka.
Looking for Orion's Belt is the easiest way to lo ...
this
runaway star has been observed to be moving through the
interstellar medium
In astronomy, the interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstella ...
at a speed of , creating a
bow shock
In astrophysics, a bow shock occurs when the magnetosphere of an astrophysical object interacts with the nearby flowing ambient plasma such as the solar wind. For Earth and other magnetized planets, it is the boundary at which the speed of t ...
over four light-years wide.
In 1920, Betelgeuse became the first extrasolar star whose
photosphere
The photosphere is a star's outer shell from which light is radiated.
The term itself is derived from Ancient Greek roots, φῶς, φωτός/''phos, photos'' meaning "light" and σφαῖρα/''sphaira'' meaning "sphere", in reference to it ...
's angular size was measured. Subsequent studies have reported an
angular diameter
The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it i ...
(i.e., apparent size) ranging from 0.042 to 0.056
arcseconds
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...
; that range of determinations is ascribed to non-sphericity,
limb darkening
Limb darkening is an optical effect seen in stars (including the Sun), where the central part of the disk appears brighter than the edge, or ''limb''. Its understanding offered early solar astronomers an opportunity to construct models with such ...
,
pulsations and varying appearance at different
wavelengths
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...
. It is also surrounded by a complex, asymmetric
envelope
An envelope is a common packaging item, usually made of thin, flat material. It is designed to contain a flat object, such as a letter or card.
Traditional envelopes are made from sheets of paper cut to one of three shapes: a rhombus, a ...
, roughly 250 times the size of the star, caused by
mass loss Stellar mass loss is a phenomenon observed in stars. All stars lose some mass over their lives at widely varying rates. Triggering events can cause the sudden ejection of a large portion of the star's mass. Stellar mass loss can also occur when a st ...
from the star itself. The Earth-observed angular diameter of Betelgeuse is exceeded only by those of
R Doradus and the Sun.
Starting in October 2019, Betelgeuse began to dim noticeably, and by mid-February 2020 its brightness had dropped by a factor of approximately 3, from magnitude 0.5 to 1.7. By 22 February 2020, Betelgeuse stopped dimming and started to brighten again; and, as reported on 25 February 2022, has remained in a more normal brightness range. Infrared observations found no significant change in brightness over the last 50 years, suggesting that the dimming was due to a change in
extinction
Extinction is the termination of a kind of organism or of a group of kinds ( taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed ...
or "large-grain
circumstellar dust", rather than an underlying change in the luminosity of the star. A 2022 study using the
Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most ver ...
suggests that occluding dust was created by a surface mass ejection. This surface mass ejection cast material millions of miles from the star that then cooled to form the dust that caused the star's dimming.
Nomenclature
The star's
designation
Designation may refer to:
* Designation (law), the process of determining an incumbent's successor
* Professional certification
* Designation (landmarks), an official classification determined by a government agency or historical society
* Designa ...
is ''α Orionis'' (Latinised to ''Alpha Orionis''), given by
Johann Bayer
Johann Bayer (1572 – 7 March 1625) was a German lawyer and uranographer (celestial cartographer). He was born in Rain, Lower Bavaria, in 1572. At twenty, in 1592 he began his study of philosophy and law at the University of Ingolstadt, ...
in 1603.
The traditional name ''Betelgeuse'' has been derived from the
Arabic
Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walte ...
' "the hand of ''al-Jauzā’''
.e. Orion.
An error, in the 13th century AD, reading the Arabic ''ya'' as ''ba'' led to the European name. In English, there are four common pronunciations of this name, depending on whether the first ''e'' is pronounced short or long and whether the ''s'' is pronounced "s" or "z":
*
*
*
*
The last pronunciation has been popularized for sounding like "
beetle juice".
In 2016, the
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...
organized a
Working Group on Star Names
The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize List of proper names of stars, proper names for stars for the international astronomical community. It operates under ...
(WGSN)
[
] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016
[
] included a table of the first two batches of names approved by the WGSN, which included ''Betelgeuse'' for this star. It is now so entered in the IAU Catalog of Star Names.
[
]
Observational history
Betelgeuse and its red coloration have been noted since
antiquity
Antiquity or Antiquities may refer to:
Historical objects or periods Artifacts
*Antiquities, objects or artifacts surviving from ancient cultures
Eras
Any period before the European Middle Ages (5th to 15th centuries) but still within the histo ...
; the classical astronomer
Ptolemy
Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of import ...
described its color as ὑπόκιρρος (''hypókirrhos'' = more or less orange-tawny), a term that was later described by a translator of
Ulugh Beg
Mīrzā Muhammad Tāraghay bin Shāhrukh ( chg, میرزا محمد طارق بن شاہ رخ, fa, میرزا محمد تراغای بن شاہ رخ), better known as Ulugh Beg () (22 March 1394 – 27 October 1449), was a Timurid sultan, as ...
's ''
Zij-i Sultani
''Zīj-i Sulṭānī'' ( fa, زیجِ سلطانی) is a Zij astronomical table and star catalogue that was published by Ulugh Beg in 1438–1439. It was the joint product of the work of a group of Muslim astronomers working under the patronage ...
'' as ''rubedo'',
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
for "ruddiness".
In the nineteenth century, before modern systems of
stellar classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting t ...
,
Angelo Secchi
Angelo Secchi (; 28 June 1818 – 26 February 1878) was an Italian Catholic priest, astronomer from the Italian region of Emilia. He was director of the observatory at the Pontifical Gregorian University (then called the Roman College) for ...
included Betelgeuse as one of the prototypes for his
Class III (orange to red) stars. By contrast, three centuries before Ptolemy, Chinese astronomers observed Betelgeuse as having a ''yellow'' color; if accurate, such an observation could suggest the star was in a
yellow supergiant phase around this time,
[
] a possibility given current research into the complex circumstellar environment of these stars.
Nascent discoveries
Aboriginal groups in South Australia have shared oral tales of the variable brightness of Betelgeuse for at least 1,000 years.
The variation in Betelgeuse's brightness was described in 1836 by
Sir John Herschel
Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint and did botanical w ...
, when he published his observations in ''Outlines of Astronomy''. From 1836 to 1840, he noticed significant changes in magnitude when Betelgeuse outshone
Rigel
Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive componentand ...
in October 1837 and again in November 1839.
A 10 year quiescent period followed; then in 1849, Herschel noted another short cycle of variability, which peaked in 1852. Later observers recorded unusually high
maxima with an interval of years, but only small variations from 1957 to 1967. The records of the
American Association of Variable Star Observers
The American Association of Variable Star Observers (AAVSO) is an international nonprofit organization, founded in 1911, focused on coordinating, analyzing, publishing, and archiving variable star observations made largely by amateur astronomers ...
(AAVSO) show a maximum
brightness
Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light. In other words, brightness is the perception elicited by the luminance of a visual target. The perception is not linear to luminance, ...
of 0.2 in 1933 and 1942, and a minimum of 1.2, observed in 1927 and 1941.
[
][
] This variability in brightness may explain why
Johann Bayer
Johann Bayer (1572 – 7 March 1625) was a German lawyer and uranographer (celestial cartographer). He was born in Rain, Lower Bavaria, in 1572. At twenty, in 1592 he began his study of philosophy and law at the University of Ingolstadt, ...
, with the publication of his ''
Uranometria
''Uranometria'' is a star atlas produced by Johann Bayer. It was published in Augsburg in 1603 by Christoph Mangle (''Christophorus Mangus'') under the full title ''Uranometria: omnium asterismorum continens schemata, nova methodo delineata, a ...
'' in 1603, designated the star ''alpha'' as it probably rivaled the usually brighter Rigel (''beta'').
[
] From Arctic latitudes, Betelgeuse's red colour and higher location in the sky than Rigel meant the
Inuit
Inuit (; iu, ᐃᓄᐃᑦ 'the people', singular: Inuk, , dual: Inuuk, ) are a group of culturally similar indigenous peoples inhabiting the Arctic and subarctic regions of Greenland, Labrador, Quebec, Nunavut, the Northwest Territories, ...
regarded it as brighter, and one local name was ''Ulluriajjuaq'' "large star".
[
]
In 1920,
Albert Michelson
Albert Abraham Michelson FFRS HFRSE (surname pronunciation anglicized as "Michael-son", December 19, 1852 – May 9, 1931) was a German-born American physicist of Polish/Jewish origin, known for his work on measuring the speed of light and espe ...
and
Francis Pease mounted a 6 meter
interferometer
Interferometry is a technique which uses the '' interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber o ...
on the front of the 2.5 meter
telescope
A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to obse ...
at
Mount Wilson Observatory
The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles.
The observ ...
. Helped by
John Anderson, the trio measured the angular diameter of Betelgeuse at 0.047
″, a figure which resulted in a diameter of () based on the
parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby object ...
value of .
[
] However, limb darkening and measurement errors resulted in uncertainty about the accuracy of these measurements.
The 1950s and 1960s saw two developments that would affect stellar
convection
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the c ...
theory in red supergiants: the
Stratoscope projects and the 1958 publication of ''Structure and Evolution of the Stars'', principally the work of
Martin Schwarzschild
Martin Schwarzschild (May 31, 1912 – April 10, 1997) was a German-American astrophysicist.
Biography
Schwarzschild was born in Potsdam into a distinguished German Jewish academic family. His father was the physicist Karl Schwarzschild and ...
and his colleague at
Princeton University
Princeton University is a private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth as the College of New Jersey, Princeton is the fourth-oldest institution of higher education in the United States and one of the n ...
, Richard Härm.
[
][
] This book disseminated ideas on how to apply computer technologies to create stellar models, while the Stratoscope projects, by taking balloon-borne telescopes above the Earth's
turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...
, produced some of the finest images of
solar granules and
sunspots ever seen, thus confirming the existence of convection in the solar atmosphere.
Imaging breakthroughs
In the 1970s, astronomers saw some major advances in astronomical imaging technology, beginning with
Antoine Labeyrie
Antoine is a French given name (from the Latin ''Antonius'' meaning 'highly praise-worthy') that is a variant of Danton, Titouan, D'Anton and Antonin.
The name is used in France, Switzerland, Belgium, Canada, West Greenland, Haiti, French Guiana, ...
's invention of
speckle interferometry, a process that significantly reduced the blurring effect caused by
astronomical seeing
In astronomy, seeing is the degradation of the image of an astronomical object due to turbulence in the atmosphere of Earth that may become visible as blurring, twinkling or variable distortion. The origin of this effect are rapidly changing ...
. It increased the
optical resolution
Optical resolution describes the ability of an imaging system to resolve detail, in the object that is being imaged.
An imaging system may have many individual components, including one or more lenses, and/or recording and display components. ...
of ground-based
telescope
A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to obse ...
s, allowing for more precise measurements of Betelgeuse's photosphere.
[
][
] With improvements in
infrared telescopy
Infrared astronomy is a sub-discipline of astronomy which specializes in the observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in bet ...
atop
Mount Wilson,
Mount Locke
Mount is often used as part of the name of specific mountains, e.g. Mount Everest.
Mount or Mounts may also refer to:
Places
* Mount, Cornwall, a village in Warleggan parish, England
* Mount, Perranzabuloe, a hamlet in Perranzabuloe parish ...
, and
Mauna Kea
Mauna Kea ( or ; ; abbreviation for ''Mauna a Wākea''); is a dormant volcano on the island of Hawaii. Its peak is above sea level, making it the highest point in the state of Hawaii and second-highest peak of an island on Earth. The peak i ...
in Hawaii, astrophysicists began peering into the complex circumstellar shells surrounding the supergiant,
[
][
][
] causing them to suspect the presence of huge gas bubbles resulting from convection.
[
] But it was not until the late 1980s and early 1990s, when Betelgeuse became a regular target for
aperture masking interferometry, that breakthroughs occurred in visible-light and
infrared imaging
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
. Pioneered by
John E. Baldwin and colleagues of the
Cavendish Astrophysics Group
The Cavendish Astrophysics Group (formerly the Radio Astronomy Group) is based at the Cavendish Laboratory at the University of Cambridge. The group operates all of the telescopes at the Mullard Radio Astronomy Observatory except for the 32m MERL ...
, the new technique employed a small mask with several holes in the telescope pupil plane, converting the
aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane.
An ...
into an ad hoc interferometric array.
[
] The technique contributed some of the most accurate measurements of Betelgeuse while revealing bright spots on the star's photosphere.
[
][
][
] These were the first optical and infrared images of a stellar disk other than the
Sun, taken first from ground-based interferometers and later from higher-resolution observations of the
COAST telescope. The "bright patches" or "hotspots" observed with these instruments appeared to corroborate a theory put forth by Schwarzschild decades earlier of massive
convection
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the c ...
cells dominating the stellar surface.
[
][
]
In 1995, the
Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most ver ...
's
Faint Object Camera
The Faint Object Camera (FOC) was a camera installed on the Hubble Space Telescope from launch in 1990 until 2002. It was replaced by the Advanced Camera for Surveys. In December 1993, Hubble's vision was corrected on STS-61 by installing COSTAR ...
captured an
ultraviolet image with a resolution superior to that obtained by ground-based interferometers—the first conventional-telescope image (or "direct-image" in NASA terminology) of the disk of another star.
[
] Because
ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiati ...
light is absorbed by the
Earth's atmosphere
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...
, observations at these wavelengths are best performed by
space telescope
A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO-2 launch ...
s.
[
] Like earlier pictures, this image contained a bright patch indicating a region in the southwestern quadrant hotter than the stellar surface. Subsequent ultraviolet spectra taken with the
Goddard High Resolution Spectrograph
The Goddard High Resolution Spectrograph (GHRS or HRS) was an ultraviolet spectrograph installed on the Hubble Space Telescope during its original construction, and it was launched into space as part of that space telescope aboard the Space Shutt ...
suggested that the hot spot was one of Betelgeuse's poles of rotation. This would give the rotational axis an inclination of about 20° to the direction of Earth, and a
position angle
In astronomy, position angle (usually abbreviated PA) is the convention for measuring angles on the sky. The International Astronomical Union defines it as the angle measured relative to the north celestial pole (NCP), turning positive into the ...
from
celestial North of about 55°.
[
]
2000s studies
In a study published in December 2000, the star's diameter was measured with the
Infrared Spatial Interferometer
The Infrared Spatial Interferometer (ISI) is an astronomical interferometer array of three telescopes operating in the mid- infrared. The telescopes are fully mobile and their current site on Mount Wilson allows for placements as far as apar ...
(ISI) at mid-infrared wavelengths producing a limb-darkened estimate of – a figure entirely consistent with Michelson's findings eighty years earlier.
[
] At the time of its publication, the estimated parallax from the
Hipparcos
''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial obj ...
mission was , yielding an estimated radius for Betelgeuse of . However, an infrared interferometric study published in 2009 announced that the star had shrunk by 15% since 1993 at an increasing rate without a significant diminution in magnitude.
[
] Subsequent observations suggest that the apparent contraction may be due to shell activity in the star's extended atmosphere.
[
]
In addition to the star's diameter, questions have arisen about the complex dynamics of Betelgeuse's extended atmosphere. The mass that makes up galaxies is recycled as
stars are formed and destroyed, and red supergiants are major contributors, yet the process by which mass is lost remains a mystery.
[
] With advances in interferometric methodologies, astronomers may be close to resolving this conundrum. In July 2009, images released by the
European Southern Observatory
The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 mem ...
, taken by the ground-based
Very Large Telescope
The Very Large Telescope (VLT) is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each with a primary mirror 8.2 m across, ...
Interferometer (VLTI), showed a vast plume of gas extending from the star into the surrounding atmosphere.
[
] This mass ejection was equal to the distance between the Sun and
Neptune
Neptune is the eighth planet from the Sun and the farthest known planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 time ...
and is one of multiple events occurring in Betelgeuse's surrounding atmosphere. Astronomers have identified at least six shells surrounding Betelgeuse. Solving the mystery of mass loss in the late stages of a star's evolution may reveal those factors that precipitate the explosive deaths of these stellar giants.
2019–20 fading
A pulsating
semiregular variable star, Betelgeuse is subject to multiple cycles of increasing and decreasing brightness due to changes in its size and temperature.
[ The astronomers who first noted the dimming of Betelgeuse, ]Villanova University
Villanova University is a private Roman Catholic research university in Villanova, Pennsylvania. It was founded by the Augustinians in 1842 and named after Saint Thomas of Villanova. The university is the oldest Catholic university in Pen ...
astronomers Richard Wasatonic and Edward Guinan
Edward F. Guinan is a professor in Villanova University's Department of Astronomy and Astrophysics. He and two colleagues observed evidence of Neptune's ring system in 1968, which was later discovered by Voyager 2 in 1989. He was also involved in ...
, and amateur Thomas Calderwood, theorize that a coincidence of a normal 5.9-year light-cycle minimum and a deeper-than-normal 425-day period are the driving factors. Other possible causes hypothesized by late-2019 were an eruption of gas or dust, or fluctuations in the star's surface brightness.[
]
By August 2020, long-term and extensive studies of Betelgeuse, primarily using ultraviolet observations by the Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most ver ...
, suggest that the unexpected dimming was probably caused by an immense amount of superhot material ejected into space. The material cooled and formed a dust cloud that blocked the starlight coming from about a quarter of Betelgeuse's surface. Hubble captured signs of dense, heated material moving through the star's atmosphere in September, October, and November before multiple telescopes observing the more marked dimming in December and the first several months of 2020.[
][
]
By January 2020, Betelgeuse had dimmed by a factor of approximately 2.5 from magnitude 0.5 to 1.5, and reported still fainter in February in '' The Astronomer's Telegram'' at a record minimum of +1.614, noting that the star is currently the "least luminous and coolest" in the 25 years of their studies and also calculating a decrease in radius. ''Astronomy
Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...
'' magazine described it as a "bizarre dimming", and popular speculation inferred that this might indicate an imminent supernova. This dropped Betelgeuse from one of the top 10 brightest stars in the sky to outside the top 20, noticeably dimmer than its near neighbor Aldebaran
Aldebaran (Arabic: “The Follower”, "الدبران") is the brightest star in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldeb ...
.[ Mainstream media reports discussed speculation that Betelgeuse might be about to explode as a supernova,][ but astronomers note that the supernova is expected to occur within approximately the next 100,000 years and is thus unlikely to be imminent.][
By 17 February 2020, Betelgeuse's brightness had remained constant for about 10 days, and the star showed signs of rebrightening. On 22 February 2020, Betelgeuse may have stopped dimming altogether, all but ending the dimming episode.] On 24 February 2020, no significant change in the infrared over the last 50 years was detected; this seemed unrelated to the recent visual fading, and suggested that an impending core collapse may be unlikely. Also on 24 February 2020, further studies suggested that occluding "large-grain circumstellar dust" may be the most likely explanation for the dimming of the star. A study that uses observation
Observation is the active acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the perception and recording of data via the use of scientific instruments. Th ...
s at submillimetre wavelengths rules out significant contributions from dust absorption. Instead, large starspot
Starspots are stellar phenomena, so-named by analogy with sunspots.
Spots as small as sunspots have not been detected on other stars, as they would cause undetectably small fluctuations in brightness. The commonly observed starspots are in gen ...
s appear to be the cause for the dimming. Followup studies, reported on 31 March 2020 in ''The Astronomer's Telegram'', found a rapid rise in the brightness of Betelgeuse.
Betelgeuse is almost unobservable from the ground between May and August because it is too close to the Sun. Before entering its 2020 conjunction
Conjunction may refer to:
* Conjunction (grammar), a part of speech
* Logical conjunction, a mathematical operator
** Conjunction introduction, a rule of inference of propositional logic
* Conjunction (astronomy), in which two astronomical bodies ...
with the Sun, Betelgeuse had reached a brightness of +0.4 . Observations with the STEREO-A spacecraft made in June and July 2020 showed that the star had dimmed by 0.5 since the last ground-based observation in April. This is surprising, because a maximum was expected for August/September 2020, and the next minimum should occur around April 2021. However, Betelgeuse's brightness is known to vary irregularly, making predictions difficult. The fading could indicate that another dimming event might occur much earlier than expected. On 30 August 2020, astronomers reported the detection of a second dust cloud emitted from Betelgeuse, and associated with recent substantial dimming (a secondary minimum on 3 August) in luminosity of the star.
In June 2021, the dust has been explained as possibly caused by a cool patch on its photosphere and in August a second independent group confirmed these results. The dust is thought to have resulted from the cooling of gas ejected from the star. An August 2022 study using the Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most ver ...
confirmed previous research and suggested the dust could have been created by a surface mass ejection. It conjectured as well the dimming could came from short-term minimum coinciding with a long-term minimum producing a grand minimum, a 416-day cycle and 2010-day cycle respectively, a mechanism first suggested by astronomer Leo Goldberg.
Observation
As a result of its distinctive orange-red color and position within Orion, Betelgeuse is easy to find with the naked eye. It is one of three stars that make up the Winter Triangle asterism, and it marks the center of the Winter Hexagon. At the beginning of January of each year, it can be seen rising in the east just after sunset. Between mid-September to mid-March (best in mid-December), it is visible to virtually every inhabited region of the globe, except in Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest co ...
at latitudes south of 82°. In May (moderate northern latitudes) or June (southern latitudes), the red supergiant can be seen briefly on the western horizon after sunset, reappearing again a few months later on the eastern horizon before sunrise. In the intermediate period (June–July), it is invisible to the naked eye (visible only with a telescope in daylight), except around midday in Antarctic regions between 70° and 80° south latitude (during polar night
The polar night is a phenomenon where the nighttime lasts for more than 24 hours that occurs in the northernmost and southernmost regions of Earth. This occurs only inside the polar circles. The opposite phenomenon, the polar day, or midnig ...
, when the Sun is below the horizon).
Betelgeuse is a variable star whose visual magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...
ranges between 0.0 and +1.6 .[ There are periods during which it surpasses Rigel to become the sixth brightest star, and occasionally it will become even brighter than ]Capella
Capella is the brightest star in the northern constellation of Auriga. It has the Bayer designation α Aurigae, which is Latinised to Alpha Aurigae and abbreviated Alpha Aur or α Aur. Capella is the sixth-brightest star ...
. At its faintest, Betelgeuse can fall behind Deneb
Deneb () is a first-magnitude star in the constellation of Cygnus, the swan. Deneb is one of the vertices of the asterism known as the Summer Triangle and the "head" of the Northern Cross. It is the brightest star in Cygnus and the ...
and Beta Crucis, themselves both slightly variable, to be the twentieth-brightest star.[
Betelgeuse has a B–V ]color index
In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. The lower the color index, the more blue (or hotter) the object is. Conversely, the larg ...
of 1.85 – a figure which points to its pronounced "redness". The photosphere has an extended atmosphere
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. ...
, which displays strong lines of emission
Emission may refer to:
Chemical products
* Emission of air pollutants, notably:
**Flue gas, gas exiting to the atmosphere via a flue
** Exhaust gas, flue gas generated by fuel combustion
** Emission of greenhouse gases, which absorb and emit radi ...
rather than absorption, a phenomenon that occurs when a star is surrounded by a thick gaseous envelope (rather than ionized). This extended gaseous atmosphere has been observed moving toward and away from Betelgeuse, depending on fluctuations in the photosphere. Betelgeuse is the brightest near-infrared source in the sky with a J band magnitude of −2.99; only about 13% of the star's radiant energy
Radiant may refer to:
Computers, software, and video games
* Radiant (software), a content management system
* GtkRadiant, a level editor created by id Software for their games
* Radiant AI, a technology developed by Bethesda Softworks for '' ...
is emitted as visible light. If human eyes were sensitive to radiation at all wavelengths, Betelgeuse would appear as the brightest star in the night sky.
Catalogues list up to nine faint visual companions to Betelgeuse. They are at distances of about one to four arc-minutes and all are fainter than 10th magnitude.
Star system
Betelgeuse is generally considered to be a single isolated star and a runaway star, not currently associated with any cluster or star-forming region, although its birthplace is unclear.
Two spectroscopic companions to Betelgeuse have been proposed. Analysis of polarization
Polarization or polarisation may refer to:
Mathematics
*Polarization of an Abelian variety, in the mathematics of complex manifolds
*Polarization of an algebraic form, a technique for expressing a homogeneous polynomial in a simpler fashion by ...
data from 1968 through 1983 indicated a close companion with a periodic orbit of about 2.1 years, and by using speckle interferometry, the team concluded that the closer of the two companions was located at (≈9 AU) from the main star with a position angle of 273°, an orbit that would potentially place it within the star's chromosphere
A chromosphere ("sphere of color") is the second layer of a star's atmosphere, located above the photosphere and below the solar transition region and corona. The term usually refers to the Sun's chromosphere, but not exclusively.
In the S ...
. The more distant companion was at (≈77 AU) with a position angle of 278°. Further studies have found no evidence for these companions or have actively refuted their existence, but the possibility of a close companion contributing to the overall flux has never been fully ruled out. High-resolution interferometry of Betelgeuse and its vicinity, far beyond the technology of the 1980s and 1990s, has not detected any companions.[
]
Distance measurements
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby object ...
is the apparent change of the position of an object, measured in seconds of arc, caused by the change of position of the observer of that object. As the Earth orbits the Sun, every star is seen to shift by a fraction of an arc second, which measure, combined with the baseline provided by the Earth's orbit gives the distance to that star. Since the first successful parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby object ...
measurement by Friedrich Bessel
Friedrich Wilhelm Bessel (; 22 July 1784 – 17 March 1846) was a German astronomer, mathematician, physicist, and geodesist. He was the first astronomer who determined reliable values for the distance from the sun to another star by the met ...
in 1838, astronomers have been puzzled by Betelgeuse's apparent distance. Knowledge of the star's distance improves the accuracy of other stellar parameters, such as luminosity
Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a s ...
that, when combined with an angular diameter, can be used to calculate the physical radius and effective temperature
The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...
; luminosity and isotopic abundances
In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomi ...
can also be used to estimate the stellar age and mass
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different element ...
.[
]
In 1920, when the first interferometric studies were performed on the star's diameter, the assumed parallax was . This equated to a distance of or roughly , producing not only an inaccurate radius for the star but every other stellar characteristic. Since then, there has been ongoing work to measure the distance of Betelgeuse, with proposed distances as high as or about .
Before the publication of the Hipparcos Catalogue
''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial ob ...
(1997), there were two slightly conflicting parallax measurements for Betelgeuse. The first, in 1991, gave a parallax of , yielding a distance of roughly or .[
] The second was the Hipparcos Input Catalogue (1993) with a trigonometric parallax of , a distance of or .[
] Given this uncertainty, researchers were adopting a wide range of distance estimates, leading to significant variances in the calculation of the star's attributes.
The results from the Hipparcos mission were released in 1997. The measured parallax of Betelgeuse was , which equated to a distance of roughly or , and had a smaller reported error than previous measurements.[
] However, later evaluation of the Hipparcos parallax measurements for variable stars like Betelgeuse found that the uncertainty of these measurements had been underestimated.[
] In 2007, an improved figure of was calculated, hence a much tighter error factor yielding a distance of roughly or .
In 2008, using the Very Large Array
The Karl G. Jansky Very Large Array (VLA) is a centimeter-wavelength radio astronomy observatory located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~ west of Socorro. The VLA comprises twent ...
(VLA), produced a radio
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transm ...
solution of , equaling a distance of or . As the researcher, Harper, points out: "The revised Hipparcos parallax leads to a larger distance () than the original; however, the astrometric
Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way.
Histor ...
solution still requires a significant cosmic noise of 2.4 mas. Given these results it is clear that the Hipparcos data still contain systematic errors of unknown origin." Although the radio data also have systematic errors, the Harper solution combines the datasets in the hope of mitigating such errors. An updated result from further observations with ALMA
Alma or ALMA may refer to:
Arts and entertainment
* ''Alma'' (film), a 2009 Spanish short animated film
* ''Alma'' (Oswald de Andrade novel), 1922
* ''Alma'' (Le Clézio novel), 2017
* ''Alma'' (play), a 1996 drama by Joshua Sobol about Alma ...
and e-Merlin gives a parallax of mas and a distance of pc or ly.
In 2020, new observational data from the space-based ''Solar Mass Ejection Imager'' aboard the Coriolis satellite and three different modeling techniques produced a refined parallax of mas, a radius of , and a distance of pc or ly, which, if accurate, would mean Betelgeuse is nearly 25% smaller and 25% closer to Earth than previously thought.
Although the European Space Agency
, owners =
, headquarters = Paris, Île-de-France, France
, coordinates =
, spaceport = Guiana Space Centre
, seal = File:ESA emblem seal.png
, seal_size = 130px
, image = Views in the Main Control Room (120 ...
's current Gaia mission
''Gaia'' is a space observatory of the European Space Agency (ESA), launched in 2013 and expected to operate until 2025. The spacecraft is designed for astrometry: measuring the positions, distances and motions of stars with unprecedented preci ...
was not expected to produce good results for stars brighter than the approximately V=6 saturation limit of the mission's instruments, actual operation has shown good performance on objects to about magnitude +3. Forced observations of brighter stars mean that final results should be available for all bright stars and a parallax for Betelgeuse will be published an order of magnitude more accurate than currently available. There is no data on Betelgeuse in Gaia Data Release 2
The ''Gaia'' catalogues are star catalogues created using the results obtained by ''Gaia'' space telescope.
The catalogues are released in stages that will contain increasing amounts of information; the early releases also miss some stars, especia ...
.
Variability
Betelgeuse is classified as a semiregular variable star, indicating that some periodicity is noticeable in the brightness changes, but amplitudes may vary, cycles may have different lengths, and there may be standstills or periods of irregularity. It is placed in subgroup SRc; these are pulsating red supergiants with amplitudes around one magnitude and periods from tens to hundreds of days.[
Betelgeuse typically shows only small brightness changes near to magnitude +0.5, although at its extremes it can become as bright as magnitude 0.0 or as faint as magnitude +1.6. Betelgeuse is listed in the ]General Catalogue of Variable Stars
The General Catalogue of Variable Stars (GCVS) is a list of variable stars. Its first edition, containing 10,820 stars, was published in 1948 by the Academy of Sciences of the USSR and edited by B. V. Kukarkin and P. P. Parenago. Second and th ...
with a possible period of 2,335 days.[ More detailed analyses have shown a main period near 400 days, a short period of 185 days,][ and a longer secondary period around 2,100 days.] The lowest reliably-recorded V-band magnitude of +1.614 was reported in February 2020.
Radial pulsations of red supergiants are well-modelled and show that periods of a few hundred days are typically due to fundamental and first overtone
An overtone is any resonant frequency above the fundamental frequency of a sound. (An overtone may or may not be a harmonic) In other words, overtones are all pitches higher than the lowest pitch within an individual sound; the fundamental i ...
pulsation. Lines in the spectrum
A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of color ...
of Betelgeuse show doppler shift
The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who ...
s indicating radial velocity
The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the rate of change of the distance or range between the two points. It is equivalent to the vector projection ...
changes corresponding, very roughly, to the brightness changes. This demonstrates the nature of the pulsations in size, although corresponding temperature and spectral variations are not clearly seen. Variations in the diameter of Betelgeuse have also been measured directly.[ First overtone pulsations of 185 days have been observed, and the ratio of the fundamental to overtone periods gives valuable information about the internal structure of the star and its age.][
The source of the long secondary periods is unknown, but they cannot be explained by ]radial pulsations
The unqualified term instability strip usually refers to a region of the Hertzsprung–Russell diagram largely occupied by several related classes of pulsating variable stars: Delta Scuti variables, SX Phoenicis variables, and rapidly oscillati ...
.[ Interferometric observations of Betelgeuse have shown hotspots that are thought to be created by massive convection cells, a significant fraction of the diameter of the star and each emitting 5–10% of the total light of the star.][ One theory to explain long secondary periods is that they are caused by the evolution of such cells combined with the rotation of the star.][ Other theories include close binary interactions, chromospheric magnetic activity influencing mass loss, or non-radial pulsations such as ]g-mode
is a Japanese company that specializes in games for Java-compatible mobile phones. The company also licenses content for mobile telecommunications operators, as well as being involved in the original equipment manufacturing of mobile phone games. ...
s.
In addition to the discrete dominant periods, small-amplitude stochastic
Stochastic (, ) refers to the property of being well described by a random probability distribution. Although stochasticity and randomness are distinct in that the former refers to a modeling approach and the latter refers to phenomena themselve ...
variations are seen. It is proposed that this is due to granulation
Granulation is the process of forming grains or granules from a powdery or solid substance, producing a granular material. It is applied in several technological processes in the chemical and pharmaceutical industries. Typically, granulation i ...
, similar to the same effect on the sun but on a much larger scale.[
]
Diameter
On 13 December 1920, Betelgeuse became the first star outside the Solar System to have the angular size of its photosphere measured. Although interferometry was still in its infancy, the experiment proved a success. The researchers, using a uniform disk model, determined that Betelgeuse had a diameter of , although the stellar disk was likely 17% larger due to the limb darkening
Limb darkening is an optical effect seen in stars (including the Sun), where the central part of the disk appears brighter than the edge, or ''limb''. Its understanding offered early solar astronomers an opportunity to construct models with such ...
, resulting in an estimate for its angular diameter of about 0.055". Since then, other studies have produced angular diameters that range from 0.042 to . Combining these data with historical distance estimates of 180 to yields a projected radius of the stellar disk of anywhere from 1.2 to . Using the Solar System for comparison, the orbit of Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmos ...
is about , Ceres in the asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...
, Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandt ...
—so, assuming Betelgeuse occupying the place of the Sun, its photosphere might extend beyond the Jovian orbit, not quite reaching Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; ...
at .
The precise diameter has been hard to define for several reasons:
# Betelgeuse is a pulsating star, so its diameter changes with time;
# The star has no definable "edge" as limb darkening causes the optical emissions to vary in color and decrease the farther one extends out from the center;
# Betelgeuse is surrounded by a circumstellar envelope composed of matter ejected from the star—matter which absorbs and emits light—making it difficult to define the photosphere of the star;
# Measurements can be taken at varying wavelengths
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...
within the electromagnetic spectrum
The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies.
The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from ...
and the difference in reported diameters can be as much as 30–35%, yet comparing one finding with another is difficult as the star's apparent size differs depending on the wavelength used. Studies have shown that the measured angular diameter is considerably larger at ultraviolet wavelengths, decreases through the visible to a minimum in the near-infrared, and increase again in the mid-infrared spectrum;
# Atmospheric twinkling limits the resolution obtainable from ground-based telescopes since turbulence degrades angular resolution.
The generally reported radii of large cool stars are Rosseland radii, defined as the radius of the photosphere at a specific optical depth of two-thirds. This corresponds to the radius calculated from the effective temperature and bolometric luminosity. The Rosseland radius differs from directly measured radii, with corrections for limb darkening
Limb darkening is an optical effect seen in stars (including the Sun), where the central part of the disk appears brighter than the edge, or ''limb''. Its understanding offered early solar astronomers an opportunity to construct models with such ...
and the observation wavelength. For example, a measured angular diameter of 55.6 mas would correspond to a Rosseland mean diameter of 56.2 mas, while further corrections for the existence of surrounding dust and gas shells would give a diameter of .[
To overcome these challenges, researchers have employed various solutions. Astronomical interferometry, first conceived by ]Hippolyte Fizeau
Armand Hippolyte Louis Fizeau FRS FRSE MIF (; 23 September 181918 September 1896) was a French physicist, best known for measuring the speed of light in the namesake Fizeau experiment.
Biography
Fizeau was born in Paris to Louis and Beatrice Fiz ...
in 1868, was the seminal concept that has enabled major improvements in modern telescopy and led to the creation of the Michelson interferometer
The Michelson interferometer is a common configuration for optical interferometry and was invented by the 19/20th-century American physicist Albert Abraham Michelson. Using a beam splitter, a light source is split into two arms. Each of those ...
in the 1880s, and the first successful measurement of Betelgeuse. Just as human depth perception
Depth perception is the ability to perceive distance to objects in the world using the visual system and visual perception. It is a major factor in perceiving the world in three dimensions. Depth perception happens primarily due to stereopsi ...
increases when two eyes instead of one perceive an object, Fizeau proposed the observation of stars through two apertures instead of one to obtain interferences that would furnish information on the star's spatial intensity distribution. The science evolved quickly and multiple-aperture interferometers are now used to capture speckled images, which are synthesized using Fourier analysis to produce a portrait of high resolution. It was this methodology that identified the hotspots on Betelgeuse in the 1990s. Other technological breakthroughs include adaptive optics
Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of incoming wavefront distortions by deforming a mirror in order to compensate for the distortion. It is used in astronomical tel ...
, space observatories like Hipparcos, Hubble
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...
and Spitzer, and the Astronomical Multi-BEam Recombiner (AMBER), which combines the beams of three telescopes simultaneously, allowing researchers to achieve milliarcsecond spatial resolution
In physics and geosciences, the term spatial resolution refers to distance between independent measurements, or the physical dimension that represents a pixel of the image. While in some instruments, like cameras and telescopes, spatial resoluti ...
.
Observations in different regions of the electromagnetic spectrum—the visible, near-infrared ( NIR), mid-infrared (MIR), or radio—produce very different angular measurements. In 1996, Betelgeuse was shown to have a uniform disk of . In 2000, a Space Sciences Laboratory
The Space Sciences Laboratory (SSL) is an Organized Research Unit (ORU) of the University of California, Berkeley. Founded in 1959, the laboratory is located in the Berkeley Hills above the university campus. It has developed and continues ...
team measured a diameter of , ignoring any possible contribution from hotspots, which are less noticeable in the mid-infrared. Also included was a theoretical allowance for limb darkening, yielding a diameter of . The earlier estimate equates to a radius of roughly or , assuming the 2008 Harper distance of , a figure roughly the size of the Jovian orbit of .
In 2004, a team of astronomers working in the near-infrared announced that the more accurate photospheric measurement was . The study also put forth an explanation as to why varying wavelengths from the visible to mid-infrared produce different diameters: the star is seen through a thick, warm extended atmosphere. At short wavelengths (the visible spectrum) the atmosphere scatters light, thus slightly increasing the star's diameter. At near-infrared wavelengths ( K and L bands), the scattering is negligible, so the classical photosphere can be directly seen; in the mid-infrared the scattering increases once more, causing the thermal emission of the warm atmosphere to increase the apparent diameter.
Studies with the IOTA
Iota (; uppercase: Ι, lowercase: ι; ) is the ninth letter of the Greek alphabet. It was derived from the Phoenician letter Yodh. Letters that arose from this letter include the Latin I and J, the Cyrillic І (І, і), Yi (Ї, ї), and ...
and VLTI published in 2009 brought strong support to the idea of dust shells and a molecular shell (MOLsphere) around Betelgeuse, and yielded diameters ranging from 42.57 to with comparatively insignificant margins of error. In 2011, a third estimate in the near-infrared corroborating the 2009 numbers, this time showing a limb-darkened disk diameter of . The near-infrared photospheric diameter of at the Hipparcos distance of equates to about or . A 2014 paper derives an angular diameter of (equivalent to a uniform disc) using H and K band observations made with the VLTI AMBER instrument.
In 2009 it was announced that the radius of Betelgeuse had shrunk from 1993 to 2009 by 15%, with the 2008 angular measurement equal to . Unlike most earlier papers, this study used measurements at one specific wavelength over 15 years. The diminution in Betelgeuse's apparent size equates to a range of values between seen in 1993 to seen in 2008—a contraction of almost in . The observed contraction is generally believed to be a variation in just a portion of the extended atmosphere around Betelgeuse, and observations at other wavelengths have shown an increase in diameter over a similar period.[
The latest models of Betelgeuse adopt a photospheric angular diameter of around , with multiple shells out to 50-.][ Assuming a distance of , this means a stellar diameter of .][
Once considered as having the largest angular diameter of any star in the sky after the Sun, Betelgeuse lost that distinction in 1997 when a group of astronomers measured R Doradus with a diameter of , although R Doradus, being much closer to Earth at about , has a linear diameter roughly one-third that of Betelgeuse.]
Physical characteristics
Betelgeuse is a very large, luminous but cool star classified as an M1-2 Ia-ab red supergiant. The letter "M" in this designation means that it is a red star belonging to the M spectral class and therefore has a relatively low photospheric temperature; the "Ia-ab" suffix luminosity class
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting th ...
indicates that it is an intermediate-luminosity supergiant, with properties partway between a normal supergiant and a luminous supergiant. Since 1943, the spectrum of Betelgeuse has served as one of the stable anchor points by which other stars are classified.
Uncertainty in the star's surface temperature, diameter, and distance make it difficult to achieve a precise measurement of Betelgeuse's luminosity, but research from 2012 quotes a luminosity of around , assuming a distance of . Studies since 2001 report effective temperatures ranging from 3,250 to 3,690 K. Values outside this range have previously been reported, and much of the variation is believed to be real, due to pulsations in the atmosphere.[ The star is also a slow rotator and the most recent velocity recorded was ][—much slower than ]Antares
Antares is the brightest star in the constellation of Scorpius. It has the Bayer designation α Scorpii, which is Latinised to Alpha Scorpii. Often referred to as "the heart of the scorpion", Antares is flanked by σ Scorpii and τ S ...
which has a rotational velocity of . The rotation period depends on Betelgeuse's size and orientation to Earth, but it has been calculated to take to turn on its axis, inclined at an angle of around to Earth.[
In 2004, astronomers using computer simulations speculated that even if Betelgeuse is not rotating it might exhibit large-scale magnetic activity in its extended atmosphere, a factor where even moderately strong fields could have a meaningful influence over the star's dust, wind and mass-loss properties.] A series of spectropolarimetric observations obtained in 2010 with the Bernard Lyot Telescope at Pic du Midi Observatory
The Pic du Midi de Bigorre or simply the Pic du Midi (elevation ) is a mountain in the French Pyrenees. It is the site of the Pic du Midi Observatory.
Pic du Midi Observatory
The Pic du Midi Observatory (french: Observatoire du Pic du Midi ...
revealed the presence of a weak magnetic field at the surface of Betelgeuse, suggesting that the giant convective motions of supergiant stars are able to trigger the onset of a small-scale dynamo effect
In physics, the dynamo theory proposes a mechanism by which a celestial body such as Earth or a star generates a magnetic field. The dynamo theory describes the process through which a rotating, convecting, and electrically conducting fluid ...
.[
]
Mass
Betelgeuse has no known orbital companions, so its mass cannot be calculated by that direct method. Modern mass estimates from theoretical modelling have produced values of , with values of – from older studies. It has been calculated that Betelgeuse began its life as a star of , based on a solar luminosity of 90,000–150,000. A novel method of determining the supergiant's mass was proposed in 2011, arguing for a current stellar mass of with an upper limit of 16.6 and lower of , based on observations of the star's intensity profile from narrow H-band interferometry and using a photospheric measurement of roughly or . Model fitting to evolutionary tracks give a current mass of , from an initial mass of .[
]
Motion
The kinematics of Betelgeuse are complex. The age of Class M supergiants with an initial mass of is roughly 10 million years.[
] Starting from its present position and motion a projection back in time would place Betelgeuse around farther from the galactic plane
The galactic plane is the plane on which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles. In actual usage, the terms ''galactic plane'' and ''galactic poles'' usual ...
—an implausible location, as there is no star formation
Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as "stellar nurseries" or "star-forming regions", collapse and form stars. As a branch of astronomy, star formation includ ...
region
In geography, regions, otherwise referred to as zones, lands or territories, are areas that are broadly divided by physical characteristics (physical geography), human impact characteristics (human geography), and the interaction of humanity and t ...
there. Moreover, Betelgeuse's projected pathway does not appear to intersect with the 25 Ori subassociation or the far younger Orion Nebula Cluster (ONC, also known as Ori OB1d), particularly since Very Long Baseline Array
The Very Long Baseline Array (VLBA) is a system of ten radio telescopes which are operated remotely from their Array Operations Center located in Socorro, New Mexico, as a part of the National Radio Astronomy Observatory (NRAO). These ten ra ...
astrometry yields a distance from Betelgeuse to the ONC of between 389 and . Consequently, it is likely that Betelgeuse has not always had its current motion through space but has changed course at one time or another, possibly the result of a nearby stellar explosion. An observation by the Herschel Space Observatory
The Herschel Space Observatory was a space observatory built and operated by the European Space Agency (ESA). It was active from 2009 to 2013, and was the largest infrared telescope ever launched until the launch of the James Webb Space Telesco ...
in January 2013 revealed that the star's winds are crashing against the surrounding interstellar medium.
The most likely star-formation scenario for Betelgeuse is that it is a runaway star from the Orion OB1 association. Originally a member of a high-mass multiple system within Ori OB1a, Betelgeuse was probably formed about 10–12 million years ago, but has evolved rapidly due to its high mass. In 2015, H. Bouy and J. Alves suggested that Betelgeuse may instead be a member of the newly discovered Taurion OB association
In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space.
Stellar kinematics encompasses the measurement of stellar velocities in the Milky Way and its satellites as well as ...
.
Circumstellar dynamics
In the late phase of stellar evolution
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is con ...
, massive stars like Betelgeuse exhibit high rates of mass loss Stellar mass loss is a phenomenon observed in stars. All stars lose some mass over their lives at widely varying rates. Triggering events can cause the sudden ejection of a large portion of the star's mass. Stellar mass loss can also occur when a st ...
, possibly as much as every , resulting in a complex circumstellar environment that is constantly in flux. In a 2009 paper, stellar mass loss was cited as the "key to understanding the evolution of the universe from the earliest cosmological times to the current epoch, and of planet formation and the formation of life itself".[
] However, the physical mechanism is not well understood. When Martin Schwarzschild
Martin Schwarzschild (May 31, 1912 – April 10, 1997) was a German-American astrophysicist.
Biography
Schwarzschild was born in Potsdam into a distinguished German Jewish academic family. His father was the physicist Karl Schwarzschild and ...
first proposed his theory of huge convection cells, he argued it was the likely cause of mass loss in evolved supergiants like Betelgeuse. Recent work has corroborated this hypothesis, yet there are still uncertainties about the structure of their convection, the mechanism of their mass loss, the way dust forms in their extended atmosphere, and the conditions which precipitate their dramatic finale as a type II supernova. In 2001, Graham Harper estimated a stellar wind at every , but research since 2009 has provided evidence of episodic mass loss making any total figure for Betelgeuse uncertain. Current observations suggest that a star like Betelgeuse may spend a portion of its lifetime as a red supergiant
Red supergiants (RSGs) are stars with a supergiant luminosity class ( Yerkes class I) of spectral type K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelgeuse and Antar ...
, but then cross back across the H-R diagram, pass once again through a brief yellow supergiant phase and then explode as a blue supergiant
A blue supergiant (BSG) is a hot, luminous star, often referred to as an OB supergiant. They have luminosity class I and spectral class B9 or earlier.
Blue supergiants are found towards the top left of the Hertzsprung–Russell diagram, above a ...
or Wolf-Rayet star.
Astronomers may be close to solving this mystery. They noticed a large plume of gas extending at least six times its stellar radius indicating that Betelgeuse is not shedding matter evenly in all directions. The plume's presence implies that the spherical symmetry of the star's photosphere, often observed in the infrared, is ''not'' preserved in its close environment. Asymmetries on the stellar disk had been reported at different wavelengths. However, due to the refined capabilities of the NACO adaptive optics on the VLT, these asymmetries have come into focus. The two mechanisms that could cause such asymmetrical mass loss, were large-scale convection cells or polar mass loss, possibly due to rotation. Probing deeper with ESO's AMBER, gas in the supergiant's extended atmosphere has been observed vigorously moving up and down, creating bubbles as large as the supergiant itself, leading his team to conclude that such stellar upheaval is behind the massive plume ejection observed by Kervella.[
]
Asymmetric shells
In addition to the photosphere, six other components of Betelgeuse's atmosphere have now been identified. They are a molecular environment otherwise known as the MOLsphere, a gaseous envelope, a chromosphere, a dust environment and two outer shells (S1 and S2) composed of carbon monoxide
Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...
(CO). Some of these elements are known to be asymmetric while others overlap.
At about 0.45 stellar radii (~2–) above the photosphere, there may lie a molecular layer known as the MOLsphere or molecular environment. Studies show it to be composed of water vapor and carbon monoxide with an effective temperature of about .[
] Water vapor had been originally detected in the supergiant's spectrum in the 1960s with the two Stratoscope projects but had been ignored for decades. The MOLsphere may also contain SiO
Sio may refer to:
Places
* Sió, an artificial channel in Hungary
* Siø, a small Danish island in the South Funen Archipelago
* Sio, Burkina Faso, a village in Burkina Faso
* Sio, Mali, a commune in Mali
* Sio, Papua New Guinea, a town in ...
and Al2O3—molecules which could explain the formation of dust particles.
The asymmetric gaseous envelope, another cooler region, extends for several radii (~10–) from the photosphere. It is enriched in oxygen and especially in nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seve ...
relative to carbon. These composition anomalies are likely caused by contamination by CNO-processed material from the inside of Betelgeuse.
Radio-telescope images taken in 1998 confirm that Betelgeuse has a highly complex atmosphere, with a temperature of , similar to that recorded on the star's surface but much lower than surrounding gas in the same region.[
] The VLA images also show this lower-temperature gas progressively cools as it extends outward. Although unexpected, it turns out to be the most abundant constituent of Betelgeuse's atmosphere. "This alters our basic understanding of red-supergiant star atmospheres", explained Jeremy Lim, the team's leader. "Instead of the star's atmosphere expanding uniformly due to gas heated to high temperatures near its surface, it now appears that several giant convection cells propel gas from the star's surface into its atmosphere." This is the same region in which Kervella's 2009 finding of a bright plume, possibly containing carbon and nitrogen and extending at least six photospheric radii in the southwest direction of the star, is believed to exist.
The chromosphere
A chromosphere ("sphere of color") is the second layer of a star's atmosphere, located above the photosphere and below the solar transition region and corona. The term usually refers to the Sun's chromosphere, but not exclusively.
In the S ...
was directly imaged by the Faint Object Camera on board the Hubble Space Telescope in ultraviolet wavelengths. The images also revealed a bright area in the southwest quadrant of the disk. The average radius of the chromosphere in 1996 was about 2.2 times the optical disk (~) and was reported to have a temperature no higher than . However, in 2004 observations with the STIS, Hubble's high-precision spectrometer, pointed to the existence of warm chromospheric plasma at least one arcsecond away from the star. At a distance of , the size of the chromosphere could be up to .[
] The observations have conclusively demonstrated that the warm chromospheric plasma spatially overlaps and co-exists with cool gas in Betelgeuse's gaseous envelope as well as with the dust in its circumstellar dust shells.
The first claim of a dust shell surrounding Betelgeuse was put forth in 1977 when it was noted that dust shells around mature stars often emit large amounts of radiation in excess of the photospheric contribution. Using heterodyne interferometry, it was concluded that the red supergiant emits most of its excess radiation from positions beyond 12 stellar radii or roughly the distance of the Kuiper belt
The Kuiper belt () is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 t ...
at 50 to 60 AU, which depends on the assumed stellar radius. Since then, there have been studies done of this dust envelope at varying wavelengths yielding decidedly different results. Studies from the 1990s have estimated the inner radius of the dust shell anywhere from 0.5 to , or 100 to .[
][
] These studies point out that the dust environment surrounding Betelgeuse is not static. In 1994, it was reported that Betelgeuse undergoes sporadic decades-long dust production, followed by inactivity. In 1997, significant changes in the dust shell's morphology in one year were noted, suggesting that the shell is asymmetrically illuminated by a stellar radiation field strongly affected by the existence of photospheric hotspots. The 1984 report of a giant asymmetric dust shell () has not been corroborated by recent studies, although another published the same year said that three dust shells were found extending four light-years from one side of the decaying star, suggesting that Betelgeuse sheds its outer layers as it moves.[
][
]
Although the exact size of the two outer CO shells remains elusive, preliminary estimates suggest that one shell extends from about 1.5 to 4.0 arcseconds
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...
and the other expands as far as 7.0 arcseconds. Assuming the Jovian orbit of as the star radius, the inner shell would extend roughly 50 to 150 stellar radii (~300 to ) with the outer one as far as 250 stellar radii (~). The Sun's heliopause is estimated at about 100 AU, so the size of this outer shell would be almost fourteen times the size of the Solar System.
Supersonic bow shock
Betelgeuse is travelling supersonically through the interstellar medium at a speed of (i.e. ~) creating a bow shock
In astrophysics, a bow shock occurs when the magnetosphere of an astrophysical object interacts with the nearby flowing ambient plasma such as the solar wind. For Earth and other magnetized planets, it is the boundary at which the speed of t ...
. The shock is not created by the star, but by its powerful stellar wind
A stellar wind is a flow of gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric. ...
as it ejects vast amounts of gas into the interstellar medium at a speed of , heating the material surrounding the star, thereby making it visible in infrared light. Because Betelgeuse is so bright, it was only in 1997 that the bow shock was first imaged. The comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or Coma (cometary), coma, and sometimes also a Comet ta ...
ary structure is estimated to be at least one parsec wide, assuming a distance of 643 light-years.
Hydrodynamic
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) and ...
simulations of the bow shock made in 2012 indicate that it is very young—less than 30,000 years old—suggesting two possibilities: that Betelgeuse moved into a region of the interstellar medium with different properties only recently or that Betelgeuse has undergone a significant transformation producing a changed stellar wind. A 2012 paper, proposed that this phenomenon was caused by Betelgeuse transitioning from a blue supergiant (BSG) to a red supergiant (RSG). There is evidence that in the late evolutionary stage of a star like Betelgeuse, such stars "may undergo rapid transitions from red to blue and vice versa on the Hertzsprung-Russell diagram, with accompanying rapid changes to their stellar winds and bow shocks." Moreover, if future research bears out this hypothesis, Betelgeuse may prove to have traveled close to 200,000 AU as a red supergiant scattering as much as along its trajectory.
Life phases
Betelgeuse is a red supergiant that has evolved from an O-type main sequence star. Its core will eventually collapse, producing a supernova explosion and leaving behind a compact remnant
Remnant or remnants may refer to:
Religion
* Remnant (Bible), a recurring theme in the Bible
* Remnant (Seventh-day Adventist belief), the remnant theme in the Seventh-day Adventist Church
* ''The Remnant'' (newspaper), a traditional Catholic ...
. The details depend on the exact initial mass and other physical properties of that main sequence star.
Main sequence
The initial mass of Betelgeuse can only be estimated by testing different stellar evolutionary models to match its current observed properties. The unknowns of both the models and the current properties mean that there is considerable uncertainty in Betelgeuse's initial appearance, but its mass is usually estimated to have been in the range of , with modern models finding values of . Its chemical makeup can be reasonably assumed to have been around 70% hydrogen, 28% helium, and 2.4% heavy elements, slightly more metal-rich than the Sun but otherwise similar. The initial rotation rate is more uncertain, but models with slow to moderate initial rotation rates produce the best matches to Betelgeuse's current properties. That main sequence version of Betelgeuse would have been a hot luminous star with a spectral type such as O9V.[
A star would take between 11.5 and 15 million years to reach the red supergiant stage, with more rapidly-rotating stars taking the longest.][ Rapidly-rotating stars take 9.3 million years to reach the red supergiant stage, while stars with slow rotation take only 8.1 million years.][ These are the best estimates of Betelgeuse's current age, as the time since its ]zero age main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar He ...
stage is estimated to be 8.0–8.5 million years as a star with no rotation.[
]
After core hydrogen exhaustion
Betelgeuse's time spent as a red supergiant can be estimated by comparing mass loss rates to the observed circumstellar material, as well as the abundances of heavy elements at the surface. Estimates range from 20,000 years to a maximum of 140,000 years. Betelgeuse appears to undergo short periods of heavy mass loss and is a runaway star moving rapidly through space, so comparisons of its current mass loss to the total lost mass are difficult.[
The surface of Betelgeuse shows enhancement of nitrogen, relatively low levels of carbon, and a high proportion of 13C relative to 12C, all indicative of a star that has experienced the ]first dredge-up A dredge-up is any one of several stages in the evolution of some stars. By definition, during a ''dredge-up'', a convection zone extends all the way from the star's surface down to the layers of material that have undergone fusion. Consequently, ...
. However, the first dredge-up occurs soon after a star reaches the red supergiant phase and so this only means that Betelgeuse has been a red supergiant for at least a few thousand years. The best prediction is that Betelgeuse has already spent around 40,000 years as a red supergiant,[ having left the main sequence perhaps one million years ago.][
The current mass can be estimated from evolutionary models from the initial mass and the expected mass lost so far. For Betelgeuse, the total mass lost is predicted to be no more than about , giving a current mass of , considerably higher than estimated by other means such as pulsational properties or limb-darkening models.][
Betelgeuse's mass can also be estimated based on its position on the colormagnitudediagram (CMD). Betelgeuse's color may have changed from yellow (or possibly orange) to red in the last few thousand years, based on a 2022 review of historical records. This color change combined with CMD suggest a mass of and age of 14 Myr.
All stars more massive than about are expected to end their lives when their cores collapse, typically producing a supernova explosion. Up to about , a type II-P supernova is always produced from the red supergiant stage.]
More massive stars can lose mass quickly enough that they evolve towards higher temperatures before their cores can collapse, particularly for rotating stars and models with especially high mass loss rates. These stars can produce type II-L or type IIb supernovae from yellow or blue supergiants, or type I b/c supernovae from Wolf-Rayet stars.[
]
Models of rotating stars predict a peculiar type II supernova similar to SN 1987A from a blue supergiant
A blue supergiant (BSG) is a hot, luminous star, often referred to as an OB supergiant. They have luminosity class I and spectral class B9 or earlier.
Blue supergiants are found towards the top left of the Hertzsprung–Russell diagram, above a ...
progenitor.[ On the other hand, non-rotating models predict a type II-P supernova from a red ]supergiant
Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars s ...
progenitor.
The time until Betelgeuse explodes depends on the predicted initial conditions and on the estimate of the time already spent as a red supergiant. The total lifetime from the start of the red supergiant phase to core collapse varies from about 300,000 years for a rotating star, 550,000 years for a rotating star, and up to a million years for a non-rotating star. Given the estimated time since Betelgeuse became a red supergiant, estimates of its remaining lifetime range from a "best guess" of under 100,000 years for a non-rotating model to far longer for rotating models or lower-mass stars.[ Betelgeuse's suspected birthplace in the Orion OB1 association is the location of several previous supernovae. It is believed that runaway stars may be caused by supernovae, and there is strong evidence that ]OB star
OB stars are hot, massive stars of spectral types O or early-type B that form in loosely organized groups called OB associations. They are short lived, and thus do not move very far from where they formed within their life. During their lifet ...
s μ Columbae, AE Aurigae, and 53 Arietis
53 Arietis (abbreviated 53 Ari) is a variable star in the northern constellation of Aries. ''53 Arietis'' is the Flamsteed designation; it also bears the variable star designation UW Arietis. It is a B-type main sequence star with a stel ...
all originated from such explosions in Ori OB1 2.2, 2.7, and 4.9 million years ago.[
A typical type II-P supernova emits of ]neutrino
A neutrino ( ; denoted by the Greek letter ) is a fermion (an elementary particle with spin of ) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass ...
s and produces an explosion with a kinetic energy of . As seen from Earth, Betelgeuse as a type IIP supernova would have a peak apparent magnitude somewhere in the range −8 to −12.
This would be easily visible in daylight, with a possible brightness up to a significant fraction of the full moon
The full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective. This occurs when Earth is located between the Sun and the Moon (when the ecliptic longitudes of the Sun and Moon differ by 180°). This mean ...
, though likely not exceeding it. This type of supernova would remain at roughly constant brightness for 2–3 months before rapidly dimming. The visible light is produced mainly by the radioactive decay of cobalt
Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, ...
, and sustains its brightness due to the increasing transparency of the cooling hydrogen ejected by the supernova.[
]
Media reporting
Due to misunderstandings caused by the 2009 publication of the star's 15% contraction, apparently of its outer atmosphere,[ Betelgeuse has frequently been the subject of scare stories and rumors suggesting that it will explode within a year, and leading to exaggerated claims about the consequences of such an event.
The timing and prevalence of these rumors have been linked to broader misconceptions of astronomy, particularly to doomsday predictions relating to the Mayan calendrical apocalypse.
Betelgeuse is not likely to produce a ]gamma-ray burst
In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang. Bursts can last from ten milli ...
and is not close enough for its X-ray
X-rays (or rarely, ''X-radiation'') are a form of high-energy electromagnetic radiation. In many languages, it is referred to as Röntgen radiation, after the German scientist Wilhelm Conrad Röntgen, who discovered it in 1895 and named it ' ...
s, ultraviolet radiation, or ejected material to cause significant effects on Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surf ...
.[
Following the dimming of Betelgeuse in December 2019,][ reports appeared in the science and mainstream media that again included speculation that the star might be about to go supernova – even in the face of scientific research that a supernova is not expected for perhaps 100,000 years.][
]
Some outlets reported the magnitude as faint as +1.3 as an unusual and interesting phenomenon, like ''Astronomy'' magazine,[ the '' National Geographic'',][ and the ''Smithsonian''.
Some mainstream media, like '']The Washington Post
''The Washington Post'' (also known as the ''Post'' and, informally, ''WaPo'') is an American daily newspaper published in Washington, D.C. It is the most widely circulated newspaper within the Washington metropolitan area and has a large n ...
'',[ '']ABC News
ABC News is the journalism, news division of the American broadcast network American Broadcasting Company, ABC. Its flagship program is the daily evening newscast ''ABC World News Tonight, ABC World News Tonight with David Muir''; other progra ...
'' in Australia,[ and '']Popular Science
''Popular Science'' (also known as ''PopSci'') is an American digital magazine carrying popular science content, which refers to articles for the general reader on science and technology subjects. ''Popular Science'' has won over 58 awards, incl ...
'',
reported that a supernova was possible but unlikely, whilst other outlets falsely portrayed a supernova as an imminent realistic possibility. CNN, for example, chose the headline "A giant red star is acting weird and scientists think it may be about to explode",[
]
while the ''New York Post
The ''New York Post'' (''NY Post'') is a conservative daily tabloid newspaper published in New York City. The ''Post'' also operates NYPost.com, the celebrity gossip site PageSix.com, and the entertainment site Decider.com.
It was established ...
'' declared Betelgeuse as "due for explosive supernova".[
]
Phil Plait
Philip Cary Plait (born September 30, 1964), also known as The Bad Astronomer, is an American astronomer, skeptic, and popular science blogger. Plait has worked as part of the Hubble Space Telescope team, images and spectra of astronomical obje ...
, in his '' Bad Astronomy'' blog, noting that Betelgeuse's recent behaviour, " ile unusual . . . isn't unprecedented," argued that the star is not likely to explode "for a long, long time."[
]
Dennis Overbye of ''The New York Times
''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...
'' agreed that an explosion was not imminent but added that "astronomers are having fun thinking about it."[
]
Following the eventual supernova, a small dense remnant will be left behind, either a neutron star
A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. w ...
or black hole
A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can defo ...
. Betelgeuse does not seem to have a core massive enough for a black hole, so the remnant will probably be a neutron star of approximately .[
]
Ethnological attributes
Spelling and pronunciation
Betelgeuse has also been spelled ''Betelgeux'' and, in German
German(s) may refer to:
* Germany (of or related to)
**Germania (historical use)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizens of Germany, see also German nationality law
**Ger ...
, ''Beteigeuze'' (according to Bode).
''Betelgeux'' and ''Betelgeuze'' were used until the early 20th century, when the spelling ''Betelgeuse'' became universal.
Consensus on its pronunciation is weak and is as varied as its spellings:
* Oxford English Dictionary
The ''Oxford English Dictionary'' (''OED'') is the first and foundational historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a com ...
and Royal Astronomical Society of Canada
* Oxford English Dictionary
The ''Oxford English Dictionary'' (''OED'') is the first and foundational historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a com ...
* (Canadian Oxford Dictionary, ''Webster's Collegiate Dictionary'')
* (Martha Evans Martin, ''The Friendly Stars'')
The ''-urz'' pronunciations are attempts to render the French ''eu'' sound; they only work in ''r''-dropping accents.
Etymology
Betelgeuse is often mistranslated as "armpit of the central one". In his 1899 work '' Star-Names and Their Meanings'', American amateur naturalist Richard Hinckley Allen stated the derivation was from the ', which he claimed degenerated into a number of forms including ''Bed Elgueze'', ''Beit Algueze'', ''Bet El-gueze'', ''Beteigeuze'' and more, to the forms ''Betelgeuse'', ''Betelguese'', ''Betelgueze'' and ''Betelgeux''. The star was named ''Beldengeuze'' in the '' Alfonsine Tables'', and Italian Jesuit priest and astronomer Giovanni Battista Riccioli
Giovanni Battista Riccioli, SJ (17 April 1598 – 25 June 1671) was an Italian astronomer and a Catholic priest in the Jesuit order. He is known, among other things, for his experiments with pendulums and with falling bodies, for his discussion ...
had called it ''Bectelgeuze'' or ''Bedalgeuze''.
Paul Kunitzsch, Professor of Arabic Studies at the University of Munich, refuted Allen's derivation and instead proposed that the full name is a corruption of the Arabic ', meaning "the Hand of ''al-Jauzā'"''; ''i.e.'', Orion.
European mistransliteration into medieval Latin
Medieval Latin was the form of Literary Latin
Classical Latin is the form of Literary Latin recognized as a Literary language, literary standard language, standard by writers of the late Roman Republic and early Roman Empire. It was used f ...
led to the first character ''y'' (ﻴ, with two dots underneath) being misread as a ''b'' (ﺒ, with only one dot underneath).
During the Renaissance
The Renaissance ( , ) , from , with the same meanings. is a period in European history marking the transition from the Middle Ages to modernity and covering the 15th and 16th centuries, characterized by an effort to revive and surpass id ...
, the star's name was written as ' ("house of Orion") or ', incorrectly thought to mean "armpit of Orion" (a true translation of "armpit" would be , transliterated as '')''. This led to the modern rendering as ''Betelgeuse''. Other writers have since accepted Kunitzsch's explanation.
The last part of the name, "-elgeuse", comes from the Arabic ', a historical Arabic name of the constellation Orion, a feminine name in old Arabian legend
Religion in pre-Islamic Arabia included indigenous Arabian polytheism, ancient Semitic religions, Christianity, Judaism, Mandaeism, and Iranian religions such as Zoroastrianism, and Manichaeism, and rarely Buddhism.
Arabian polytheism, the d ...
, and of uncertain meaning. Because ', the root
In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...
of ', means "middle", ' roughly means "the Central One". The modern Arabic name for Orion is ' ("the Giant"), although the use of ' in the name of the star has continued. The 17th-century English translator Edmund Chilmead gave it the name ''Ied Algeuze'' ("Orion's Hand"), from Christmannus
Jakob Christmann (born November 1554 in Johannisberg (Rheingau), Geisenheim – 16 June 1613 in Heidelberg) was a German oriental studies, Orientalist who also studied problems of astronomy.
Life
Christmann, a Jew who converted before 1578 t ...
. Other Arabic names recorded include ' ("the Right Hand"), ' ("the Arm"), and ' ("the Shoulder"), all of al-Jauzā, Orion, as '.
Other names
Other names for Betelgeuse included the Persian ' "the Arm", and Coptic ' "an Armlet". ' was its Sanskrit
Sanskrit (; attributively , ; nominalization, nominally , , ) is a classical language belonging to the Indo-Aryan languages, Indo-Aryan branch of the Indo-European languages. It arose in South Asia after its predecessor languages had Trans-cul ...
name, as part of a Hindu understanding of the constellation as a running antelope or stag. In traditional Chinese astronomy
Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categorized in the t ...
, the name for Betelgeuse is ('', the Fourth Star of the constellation of Three Stars'') as the Chinese constellation
Traditional Chinese astronomy has a system of dividing the celestial sphere into asterisms or constellations, known as "officials" ( Chinese ''xīng guān'').
The Chinese asterisms are generally smaller than the constellations of Hellenistic ...
originally referred to the three stars in the girdle of Orion. This constellation was ultimately expanded to ten stars, but the earlier name stuck. In Japan, the Taira, or Heike, clan adopted Betelgeuse and its red color as its symbol, calling the star ''Heike-boshi'', (), while the Minamoto, or Genji, clan had chosen Rigel and its white color. The two powerful families fought a legendary war in Japanese history, the stars seen as facing each other off and only kept apart by the Belt.
In Tahitian lore, Betelgeuse was one of the pillars propping up the sky, known as ''Anâ-varu'', the pillar to sit by. It was also called ''Ta'urua-nui-o-Mere'' "Great festivity in parental yearnings". A Hawaiian term for it was ''Kaulua-koko'' "brilliant red star". The Lacandon people
The Lacandon are one of the Maya peoples who live in the Jungle (terrain), jungles of the Mexican state of Chiapas, near the southern border with Guatemala. Their homeland, the Lacandon Jungle, lies along the Mexican side of the Usumacinta River ...
of Central America knew it as ''chäk tulix'' "red butterfly".
Astronomy writer Robert Burnham Jr.
Robert Burnham Jr. (June 16, 1931 – March 20, 1993) was an American astronomer, best known for writing the classic three-volume ''Burnham's Celestial Handbook''. He is the discoverer of numerous asteroids including the Mars crossing asteroid 3 ...
proposed the term ''padparadaschah'' which denotes a rare orange sapphire in India, for the star.
Mythology
With the history of astronomy
Astronomy is the oldest of the natural sciences, dating back to antiquity, with its origins in the religious, mythological, cosmological, calendrical, and astrological beliefs and practices of prehistory: vestiges of these are still found i ...
intimately associated with mythology
Myth is a folklore genre consisting of Narrative, narratives that play a fundamental role in a society, such as foundational tales or Origin myth, origin myths. Since "myth" is widely used to imply that a story is not Objectivity (philosophy), ...
and astrology
Astrology is a range of divinatory practices, recognized as pseudoscientific since the 18th century, that claim to discern information about human affairs and terrestrial events by studying the apparent positions of celestial objects. Di ...
before the scientific revolution
The Scientific Revolution was a series of events that marked the emergence of modern science during the early modern period, when developments in mathematics, physics, astronomy, biology (including human anatomy) and chemistry transformed ...
, the red star, like the planet Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmos ...
that derives its name from a Roman war god, has been closely associated with the martial
Marcus Valerius Martialis (known in English as Martial ; March, between 38 and 41 AD – between 102 and 104 AD) was a Roman poet from Hispania (modern Spain) best known for his twelve books of ''Epigrams'', published in Rome between AD 86 an ...
archetype
The concept of an archetype (; ) appears in areas relating to behavior, historical psychology, and literary analysis.
An archetype can be any of the following:
# a statement, pattern of behavior, prototype, "first" form, or a main model that ...
of conquest for millennia, and by extension, the motif of death and rebirth. Other cultures have produced different myths. Stephen R. Wilk has proposed the constellation of Orion could have represented the Greek mythological figure Pelops
In Greek mythology, Pelops (; ) was king of Pisa in the Peloponnesus region (, lit. "Pelops' Island"). He was the son of Tantalus and the father of Atreus.
He was venerated at Olympia, where his cult developed into the founding myth of the ...
, who had an artificial shoulder of ivory made for him, with Betelgeuse as the shoulder, its color reminiscent of the reddish yellow sheen of ivory.
Aboriginal
Aborigine, aborigine or aboriginal may refer to:
*Aborigines (mythology), in Roman mythology
* Indigenous peoples, general term for ethnic groups who are the earliest known inhabitants of an area
*One of several groups of indigenous peoples, see ...
people from the Great Victoria Desert
The Great Victoria Desert is a sparsely populated desert ecoregion and interim Australian bioregion in Western Australia and South Australia.
History
In 1875, British-born Australian explorer Ernest Giles became the first European to cross th ...
of South Australia incorporated Betelgeuse into their oral traditions as the club of Nyeeruna (Orion), which fills with fire-magic and dissipates before returning. This has been interpreted as showing that early Aboriginal observers were aware of the brightness variations of Betelgeuse. The Wardaman people of northern Australia knew the star as ''Ya-jungin'' "Owl Eyes Flicking", its variable light signifying its intermittent watching of ceremonies led by the Red Kangaroo Leader Rigel. In South African mythology, Betelgeuse was perceived as a lion casting a predatory gaze toward the three zebras represented by Orion's Belt
Orion's Belt or the Belt of Orion, also known as the Three Kings or Three Sisters, is an asterism in the constellation Orion. It consists of the three bright stars Alnitak, Alnilam and Mintaka.
Looking for Orion's Belt is the easiest way to lo ...
.
In the Americas, Betelgeuse signifies a severed limb of a man-figure (Orion)—the Taulipang of Brazil know the constellation as Zililkawai, a hero whose leg was cut off by his wife, with the variable light of Betelgeuse linked to the severing of the limb. Similarly, the Lakota people of North America see it as a chief whose arm has been severed.
A Sanskrit name for Betelgeuse is ārdrā "the moist one", eponymous of the ''Ardra'' lunar mansion in Hindu astrology
Jyotisha or Jyotishya (from Sanskrit ', from ' “light, heavenly body" and ''ish'' - from Isvara or God) is the traditional Hindu system of astrology, also known as Hindu astrology, Indian astrology and more recently Vedic astrology. It is o ...
. The Rigvedic God of storms Rudra
Rudra (; sa, रुद्र) is a Rigvedic deity associated with Shiva, the wind or storms, Vayu, medicine, and the hunt. One translation of the name is 'the roarer'. In the Rigveda, Rudra is praised as the 'mightiest of the mighty'. Ru ...
presided over the star; this association was linked by 19th-century star enthusiast Richard Hinckley Allen to Orion's stormy nature. The constellations in Macedonian folklore represented agricultural items and animals, reflecting their village way of life. To them, Betelgeuse was ''Orach'' "the ploughman", alongside the rest of Orion which depicted a plough with oxen. The rising of Betelgeuse at around 3 a.m. in late summer and autumn signified the time for village men to go to the fields and plough. To the Inuit
Inuit (; iu, ᐃᓄᐃᑦ 'the people', singular: Inuk, , dual: Inuuk, ) are a group of culturally similar indigenous peoples inhabiting the Arctic and subarctic regions of Greenland, Labrador, Quebec, Nunavut, the Northwest Territories, ...
, the appearance of Betelgeuse and Bellatrix
Bellatrix is the third-brightest star in the constellation of Orion, positioned 5° west of the red supergiant Betelgeuse (Alpha Orionis). It has the Bayer designation γ Orionis, which is Latinized to Gamma Orionis. With a slightly va ...
high in the southern sky after sunset marked the beginning of spring and lengthening days in late February and early March. The two stars were known as ''Akuttujuuk'' "those (two) placed far apart", referring to the distance between them, mainly to people from North Baffin Island and Melville Peninsula.[
The opposed locations of Orion and ]Scorpius
Scorpius is a zodiac constellation located in the Southern celestial hemisphere, where it sits near the center of the Milky Way, between Libra to the west and Sagittarius to the east. Scorpius is an ancient constellation that pre-dates the G ...
, with their corresponding bright red variable stars Betelgeuse and Antares
Antares is the brightest star in the constellation of Scorpius. It has the Bayer designation α Scorpii, which is Latinised to Alpha Scorpii. Often referred to as "the heart of the scorpion", Antares is flanked by σ Scorpii and τ S ...
, were noted by ancient cultures around the world. The setting of Orion and rising of Scorpius signify the death of Orion by the scorpion. In China they signify brothers and rivals Shen and Shang. The Batak
Batak is a collective term used to identify a number of closely related Austronesian ethnic groups predominantly found in North Sumatra, Indonesia, who speak Batak languages. The term is used to include the Karo, Pakpak, Simalungun, Toba, ...
of Sumatra marked their New Year with the first new moon
In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude. At this phase, the lunar disk is not visible to the naked eye, except when it is silhouetted against the Sun during a solar eclip ...
after the sinking of Orion's Belt below the horizon, at which point Betelgeuse remained "like the tail of a rooster". The positions of Betelgeuse and Antares at opposite ends of the celestial sky were considered significant and their constellations were seen as a pair of scorpions. Scorpion days marked as nights that both constellations could be seen.
In popular culture
As one of the brightest and best-known stars, Betelgeuse has featured in many works of fiction. The star's unusual name inspired the title of the 1988 film '' Beetlejuice'', referring to its titular antagonist, and script writer Michael McDowell was impressed by how many people made the connection. In the popular science fiction series ''The Hitchhiker's Guide to the Galaxy
''The Hitchhiker's Guide to the Galaxy'' (sometimes referred to as ''HG2G'', ''HHGTTG'', ''H2G2'', or ''tHGttG'') is a comedy science fiction franchise created by Douglas Adams. Originally a 1978 radio comedy broadcast on BBC Radio 4, it ...
'' by Douglas Adams
Douglas Noel Adams (11 March 1952 – 11 May 2001) was an English author and screenwriter, best known for ''The Hitchhiker's Guide to the Galaxy''. Originally a 1978 BBC radio comedy, ''The Hitchhiker's Guide to the Galaxy'' developed into a " ...
, Ford Prefect
The Ford Prefect is a line of British cars which was produced by Ford UK between 1938 and 1961 as an upmarket version of the Ford Popular and Ford Anglia small family cars. It was introduced in October 1938 and remained in production until 19 ...
was from "a small planet somewhere in the vicinity of Betelgeuse."
Two American navy ships were named after the star, both of them World War II vessels, the launched in 1939 and launched in 1944. In 1979, a French supertanker named '' Betelgeuse'' was moored off Whiddy Island discharging oil when it exploded, killing 50 people in one of the worst disasters in Ireland's history.
The Dave Matthews Band
Dave Matthews Band (also known by the initials DMB) is an American rock band formed in Charlottesville, Virginia, in 1991. The band's founding members were singer-songwriter and guitarist Dave Matthews, bassist Stefan Lessard, drummer and back ...
song " Black and Blue Bird" references the star. The Blur song "Far Out" from their 1994 album Parklife mentions Betelgeuse in its lyrics.
The Philip Larkin
Philip Arthur Larkin (9 August 1922 – 2 December 1985) was an English poet, novelist, and librarian. His first book of poetry, ''The North Ship'', was published in 1945, followed by two novels, ''Jill'' (1946) and ''A Girl in Winter'' (1947 ...
poem "The North Ship", found in the collection of the same name, references the star in the section titled "Above 80° N", which reads:" 'A woman has ten claws,' /
Sang the drunken boatswain; /
Farther than Betelgeuse, /
More brilliant than Orion /
Or the planets Venus and Mars, /
The star flames on the ocean; /
'A woman has ten claws,' /
Sang the drunken boatswain."
Humbert Wolfe
Humbert Wolfe CB CBE (5 January 1885 – 5 January 1940) was an Italian-born British poet, man of letters and civil servant.
Biography
Humbert Wolfe was born in Milan, Italy, and came from a Jewish family background,"Wolfe, Humbert" in Stanley J ...
wrote a poem about Betelgeuse, which was set to music by Gustav Holst
Gustav Theodore Holst (born Gustavus Theodore von Holst; 21 September 1874 – 25 May 1934) was an English composer, arranger and teacher. Best known for his orchestral suite '' The Planets'', he composed many other works across a range ...
.
Table of angular diameter estimates
This table provides a non-exhaustive list of angular measurements conducted since 1920. Also included is a column providing a current range of radii for each study based on Betelgeuse's most recent distance estimate (Harper ''et al.'') of .
See also
* List of stars in Orion
This is the list of notable stars in the constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mytholog ...
* List of stars that have unusual dimming periods
This list of stars that have unusual dimming periods is a table of stars that have been observed to darken and brighten and don't appear to be eclipsing binaries or intrinsic variables. It's based on studies searching for analogs of Tabby's ...
References
Notes
Citations
External links
Surface imaging of Betelgeuse with COAST and the WHT
– interferometric images taken at different wavelengths
– Infrared Processing and Analysis Center (IPAC) webpage showing pictures at various wavelengths
* APOD Pictures:
Mars and Orion over Monument Valley
skyscape showing the relative brightness of Betelgeuse and Rigel
breathtaking vista the Orion molecular cloud complex from Rogelio Bernal Andreo
– a reconstructed image showing two hotspots, possibly convection cells
– Freytag's "Star in a Box" illustrating the nature of Betelgeuse's "monster granules"
– image of Betelgeuse showing the effect of atmospheric twinkling in a telescope
– numerical simulation of a red supergiant star like Betelgeuse
{{DEFAULTSORT:Betelgeuse
M-type supergiants
Semiregular variable stars
Runaway stars
Orion (constellation)
Orionis, Alpha
Durchmusterung objects
Orionis, 58
039801
027989
2061
In contemporary history, the third millennium of the anno Domini or Common Era in the Gregorian calendar is the current millennium spanning the years 2001 to 3000 (21st to 30th centuries). Ongoing futures studies seek to understand what is l ...
Stars named from the Ancient Greek language
TIC objects