47 Ursae Majoris (abbreviated 47 UMa), formally named Chalawan , is a

yellow dwarf star A G-type main-sequence star (Spectral type: G-V), also often, and imprecisely called a yellow dwarf, or G star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.9 to 1.1 solar masses and an effective tempe ...

approximately 46 light-years from Earth in the constellation of

Ursa Major Ursa Major (; also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear," referring to and contrasting it with nearby Ursa ...

. , three

extrasolar planet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

s (designated

47 Ursae Majoris b 47 Ursae Majoris b (abbreviated 47 UMa b), formally named Taphao Thong , is a gas planet and an extrasolar planet approximately 46 light-years from Earth in the constellation of Ursa Major. The planet was discovered located in a long-period o ...

, c and d; the first two later named Taphao Thong and Taphao Kaew) are believed to orbit the star. The star is located fairly close to the

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 ...

: according to astrometric measurements made by the Hipparcos astrometry

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioi ...

, it exhibits a parallax of 71.11

milliarcsecond 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 n ...

s, corresponding to a distance of 45.913 light-years. With an

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 ...

of +5.03, it is 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 ...

and its

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...

of +4.29 implies a visual

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 st ...

around 60% greater than the Sun. A

solar analog Solar-type star, solar analogs (also analogues), and solar twins are stars that are particularly similar to the Sun. The stellar classification is a hierarchy with solar twin being most like the Sun followed by solar analog and then solar-type ...

, with a

spectral type In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...

of G1V, it has a similar

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 elementar ...

to that of the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

but is slightly hotter at around 5,882 K. and slightly more

metal-rich In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as ...

with around 110% of the solar

abundance Abundance may refer to: In science and technology * Abundance (economics), the opposite of scarcities * Abundance (ecology), the relative representation of a species in a community * Abundance (programming language), a Forth-like computer prog ...

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

. Like the Sun, 47 Ursae Majoris is on the

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 Her ...

, converting

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...

in its core by

nuclear fusion Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles ( neutrons or protons). The difference in mass between the reactants and products is manifest ...

. Based on its

chromospheric activity 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 star may be around six billion years old, though evolutionary models suggest an older age of around 8.7 billion years. Other studies have yielded estimates of 4.4 and 7 billion years for the star. The low level of

magnetic activity A stellar magnetic field is a magnetic field generated by the motion of conductive plasma inside a star. This motion is created through convection, which is a form of energy transport involving the physical movement of material. A localized mag ...

makes it a Maunder Minimum candidate star.

Nomenclature

47 Ursae Majoris is the

Flamsteed designation A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the modern constellations visible from southern England. They are named for John Flamsteed who first used them while co ...

. On their discoveries the planets were successively designated 47 Ursae Majoris b, c and d. In July 2014 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, outreac ...

launched

NameExoWorlds NameExoWorlds (also known as IAU NameExoWorlds) is the name of various projects managed by the International Astronomical Union (I.A.U.) to encourage names to be submitted for astronomical objects, which would later be considered for official ad ...

, a process for giving proper names to certain exoplanets and their host stars. The process involved public nomination and voting for the new names. In December 2015, the IAU announced the winning names were Chalawan for this star and Taphao Thong and Taphao Kaew for two of the planets (b and c, respectively). The winning names were submitted by the Thai Astronomical Society,

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...

. Chalawan ( th, ชาละวัน ) is a

myth 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), ...

ological crocodile king from the Thai folktale

Krai Thong ''Krai Thong'' or ''Kraithong'' ( th, ไกรทอง, ) is a Thai folktale, originating from Phichit Province. It tells the story of Chalawan, a crocodile lord who abducts a daughter of a wealthy Phichit man, and Kraithong, a merchant from No ...

and Taphaothong and Taphaokaeo are two sisters associated with the tale. ('

Chalawan ''Krai Thong'' or ''Kraithong'' ( th, ไกรทอง, ) is a Thai folktale, originating from Phichit Province. It tells the story of Chalawan, a crocodile lord who abducts a daughter of a wealthy Phichit man, and Kraithong, a merchant from No ...

' is also the name given to an

extinct 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 and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of crocodylian. It contains a single species, ''Chalawan thailandicus''.) In 2016, the IAU 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 proper names for stars for the international astronomical community. It operates under Division C – Education ...

(WGSN) to catalog and standardize proper names for stars. In its first bulletin of July 2016, the WGSN explicitly recognized the names of exoplanets and their host stars approved by the Executive Committee Working Group Public Naming of Planets and Planetary Satellites, including the names of stars adopted during the 2015 NameExoWorlds campaign. This star is now so entered in the IAU Catalog of Star Names.

Planetary system

In 1996 an

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

( 47 UMa b) was announced in orbit around 47 Ursae Majoris by

Geoffrey Marcy Geoffrey William Marcy (born September 29, 1954) is an American astronomer. He was an early influence in the field of exoplanet detection, discovery, and characterization. Marcy was a professor of astronomy at the University of California, Berk ...

and

R. Paul Butler Robert Paul Butler (born 1960) is an astronomer and staff scientist at the Carnegie Institution for Science in Washington, D.C., who searches for extrasolar planets. he and his team have discovered over half of the planets found orbiting nea ...

. The discovery was made by observing the

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 d ...

of the star's

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 colors i ...

corresponding to changes in the star's

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 temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

as the planet's

gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...

pulled it around. The planet was the first long-period extrasolar planet discovered. Unlike the majority of known such planets, it has a low-eccentricity orbit. The planet is at least 2.53 times the mass of

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, 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 ...

and takes 1,078 days, or 2.95 years, to orbit its star. If it were to be located in the Solar System, it would lie between the orbits of

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

and Jupiter. 47UMaOrbits

In 2001, preliminary astrometric measurements made by the Hipparcos probe suggested the orbit of 47 UMa b is

inclined Incline, inclined, inclining, or inclination may refer to: *Grade (slope), the tilt, steepness, or angle from horizontal of a topographic feature (hillside, meadow, etc.) or constructed element (road, railway, field, etc.) *Slope, the tilt, steepn ...

at an angle of 63.1° to the plane of the sky, implying the planet's

true mass In astronomy, minimum mass is the lower-bound calculated mass of observed objects such as planets, stars and binary systems, nebulae, and black holes. Minimum mass is a widely cited statistic for extrasolar planets detected by the radial veloci ...

is around 2.9 times that of Jupiter. However, subsequent analysis suggested the Hipparcos measurements were not precise enough to accurately determine the orbits of substellar companions, and the inclination and true mass remain unknown. A second planet ( 47 UMa c) was announced in 2002 by

Debra Fischer Debra Ann Fischer is a professor of astronomy at Yale University researching detection and characterization of exoplanets. She was part of the team to discover the first known multiple-planet system. Education Fischer received her degree from ...

, Geoffrey Marcy and R. Paul Butler. The discovery was made using the same

method. According to Fischer et al., the planet takes around 2,391 days, or 6.55 years, to complete an orbit. This configuration is similar to the configuration of Jupiter and

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; h ...

in the Solar System, with the orbital ratio (close to 5:2) and mass ratio roughly similar. Subsequent measurements failed to confirm the existence of the second planet, and it was noted that the dataset used to determine its existence left the planet's parameters "almost unconstrained". Analysis of a longer dataset spanning over 6,900 days suggests that while a second planet in the system is likely, periods near 2,500 days have a high false-alarm probability, and the best fit model gives an orbital period of 7,586 days at a distance of 7.73 AU from the star. Nevertheless, the parameters of the second planet are still highly uncertain. On the other hand, the Catalog of Nearby Exoplanets gives a period of 2,190 days, which would put the planets close to a 2:1 ratio of orbital periods, though the reference for these parameters is uncertain: the original Fischer ''et al.'' paper is cited as a reference in spite of the fact that it gives different parameters, though this solution has been adopted by the ''

Extrasolar Planets Encyclopaedia The Extrasolar Planets Encyclopaedia is an astronomy website, founded in Paris, France at the Meudon Observatory by Jean Schneider in February 1995, which maintains a database of all the currently known and candidate extrasolar planets, with in ...

''. In 2010, the discovery of a third planet ( 47 UMa d) was made by using the Bayesian Kepler Periodogram. Using this model of this planetary system it was determined that it is 100,000 times more likely to have three planets than two planets. This discovery was announced by Debra Fischer and P. C. Gregory. This planet has an orbital period of 14,002 days, or 38.33 years, and a semi-major axis of 11.6 AU with a moderate eccentricity of 0.16. It would be the longest-period planet discovered by the radial velocity method, although longer-period planets had previously been discovered by

direct imaging Any planet is an extremely faint light source compared to its parent star. For example, a star like the Sun is about a billion times as bright as the reflected light from any of the planets orbiting it. In addition to the intrinsic difficulty ...

and

pulsar timing Any planet is an extremely faint light source compared to its parent star. For example, a star like the Sun is about a billion times as bright as the reflected light from any of the planets orbiting it. In addition to the intrinsic difficulty of ...

. Simulations suggest that the inner part of the

habitable zone In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.J. F. Kas ...

of 47 Ursae Majoris could host a

terrestrial planet A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to the Sun: Mercury, Ve ...

in a stable orbit, though the outer regions of the habitable zone would be disrupted by the gravitational influence of the planet 47 UMa b. However, the presence of a giant planet within 2.5 AU of the star may have disrupted planet formation in the inner system, and reduced the amount of water delivered to inner planets during accretion. This may mean any terrestrial planets orbiting in the habitable zone of 47 Ursae Majoris are likely to be small and dry. , there have been two METI messages sent to 47 Ursae Majoris. Both were transmitted from

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...

's largest

radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...

— Eupatoria Planetary Radar. The first message, the

Teen Age Message The Teen Age Message (TAM) was a series of interstellar radio transmissions sent from the Yevpatoria Planetary Radar to six solar-type stars during August–September 2001. The structure of the TAM was suggested by Alexander Zaitsev, Chief Sci ...

, was sent on September 3, 2001, and it will arrive at 47 Ursae Majoris in July 2047. The second message, Cosmic Call 2, was sent on July 6, 2003, and it will arrive at 47 Ursae Majoris in May 2049. Because of its planetary system, 47 Ursae Majoris was listed as one of the top 100 target stars for

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

's former

Terrestrial Planet Finder The Terrestrial Planet Finder (TPF) was a proposed project by NASA to construct a system of space telescopes for detecting extrasolar terrestrial planets. TPF was postponed several times and finally cancelled in 2011. There were two telescope ...

mission.

Notes

References

External links

* * {{Sky, 10, 59, 28.0, +, 40, 25, 49, 45.9 G-type main-sequence stars Ursae Majoris, 47 Maunder Minimum Planetary systems with three confirmed planets Ursa Major (constellation) BD+41 2147 Ursae Majoris, 47 0407 095128 053721 4277

Nomenclature

Planetary system

See also

Notes

References

External links