VB 10 or Van Biesbroeck's star is a very small and very dim
red dwarf
''Red Dwarf'' is a British science fiction comedy franchise created by Rob Grant and Doug Naylor, which primarily consists of a television sitcom that aired on BBC Two between 1988 and 1999, and on Dave since 2009, gaining a cult following. T ...
located 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, mythological subject, or inanimate object.
The origins of the e ...
Aquila. It is part of a
binary star
A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...
system.
VB 10 is historically notable as it was the coolest, least massive and least luminous known star from its discovery in 1944 until the discovery of
LHS 2924 in 1983. VB 10 is the primary standard for the
M8V spectral class.
Although it is relatively close to Earth, at about 19 light years, VB 10 is a dim
magnitude
Magnitude may refer to:
Mathematics
*Euclidean vector, a quantity defined by both its magnitude and its direction
*Magnitude (mathematics), the relative size of an object
*Norm (mathematics), a term for the size or length of a vector
*Order of ...
17, making it difficult to image with amateur telescopes as it can get lost in the glare of the primary star.
History
VB 10 was discovered in 1944 by the astronomer
George van Biesbroeck
George A. Van Biesbroeck (or Georges-Achille Van Biesbroeck, , January 21, 1880 – February 23, 1974) was a Belgian–American astronomer. He worked at observatories in Belgium, Germany and the United States. He specialized in the observation o ...
using the
Otto Struve reflector telescope at the
McDonald Observatory
McDonald Observatory is an astronomical observatory located near unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Locke in the Davis Mountains of West Texas, with additional facil ...
. He found it while surveying the telescopic field of view of the high-
proper-motion red dwarf
''Red Dwarf'' is a British science fiction comedy franchise created by Rob Grant and Doug Naylor, which primarily consists of a television sitcom that aired on BBC Two between 1988 and 1999, and on Dave since 2009, gaining a cult following. T ...
Gliese 752 (Wolf 1055), for companions.
Wolf 1055
Gliese 752 is a binary star system in the Aquila constellation. This system is relatively nearby, at a distance of about 19 light years.
The Gliese 752 system consists of two M-type stars. The primary star is the magnitude 9 ''Glies ...
had been catalogued 25 years earlier by
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 ...
astronomer
Max Wolf
Maximilian Franz Joseph Cornelius Wolf (21 June 1863 – 3 October 1932) was a German astronomer and a pioneer in the field of astrophotography. He was the chairman of astronomy at the University of Heidelberg and director of the Heidelberg-Kà ...
using similar
astrophotographic techniques. It is designated VB 10 in the 1961 publication of
Van Biesbroeck's star catalog
In 1961 the astronomer George Van Biesbroeck published a catalog of low luminosity stars discovered using the Otto Struve refractor telescope of the McDonald Observatory in Texas.
Survey and catalog
This survey is similar to earlier dim star su ...
. Later, other astronomers began referring to it as
Van Biesbroeck's star in honor of its discoverer. Because it is so dim and so close to its much brighter
primary star, earlier
astronomical surveys
An astronomical survey is a general map or image of a region of the sky (or of the whole sky) that lacks a specific observational target. Alternatively, an astronomical survey may comprise a set of images, spectra, or other observations of obje ...
missed it even though its large
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 objects ...
and large
proper motion
Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...
should have made it stand out on
photographic plates
Photographic plates preceded photographic film as a capture medium in photography, and were still used in some communities up until the late 20th century. The light-sensitive emulsion of silver salts was coated on a glass plate, typically thinn ...
taken at different times.
Characteristics
VB 10 has an extremely low luminosity with a baseline
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 nearly 19 and an apparent magnitude of 17.3 (somewhat variable), making it very difficult to see.
Mathematical formulae for calculating
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 ...
show that, if VB 10 occupied the place of the Sun, it would shine on Earth's sky at a magnitude of −12.87—approximately the same magnitude of that 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 coordinate system, ecliptic longitudes of the Sun and Moon opp ...
.
Later researchers also noted that its mass, at 0.08 solar mass (), is right at the lower limit needed to create internal pressures and temperatures high enough to initiate
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 ...
and actually be a
star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
rather than a
brown dwarf
Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most ...
. At the time of its discovery it was the lowest-mass star known. The previous record holder for the lowest mass was
Wolf 359
Wolf 359 is a red dwarf star located in the constellation Leo, near the ecliptic. At a distance of approximately 7.9 light years from Earth, it has an apparent magnitude of 13.54 and can only be seen with a large telescope. Wolf 359 i ...
at .
VB 10 is also notable by its very large
proper motion
Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...
, moving more than one
arc second
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 ...
a year through the sky as seen from Earth.
Flare star
VB 10 is a
variable star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...
and is identified 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 thi ...
as V1298 Aquilae. It is a
UV Ceti
Luyten 726-8, also known as Gliese 65, is a binary star system that is one of Earth's nearest neighbors, at about 8.7 light years from Earth in the constellation Cetus. The two component stars are both flare stars with the variable st ...
-type variable star and is known to be subject to frequent
flare events.
Its dynamics were studied from 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 versa ...
'' in the mid-1990s. Although VB 10 has a normal low surface temperature of 2600
K it was found to produce violent flares of up to 100,000 K.
Binary star
VB 10 is the
secondary star of a bound
binary star
A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...
system. The primary is called Gliese 752, and hence VB 10 is also referred to as Gliese 752 B. The primary star is much larger and brighter. The two stars are separated by about 74 arc seconds (~434 AU).
Claims of a planetary system
In May 2009, astronomers from
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
Jet Propulsion Laboratory
The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States.
Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...
,
Pasadena, California
Pasadena ( ) is a city in Los Angeles County, California, northeast of downtown Los Angeles. It is the most populous city and the primary cultural center of the San Gabriel Valley. Old Pasadena is the city's original commercial district.
I ...
, announced that they had found evidence of a planet orbiting VB 10, which they designated VB 10b. The
Hale telescope
The Hale Telescope is a , 3.3 reflecting telescope at the Palomar Observatory in San Diego County, California, US, named after astronomer George Ellery Hale. With funding from the Rockefeller Foundation in 1928, he orchestrated the planning, de ...
at the
Palomar Observatory
Palomar Observatory is an astronomical research observatory in San Diego County, California, United States, in the Palomar Mountain Range. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...
was used to detect evidence of this planet using the
astrometry method.
The new planet was claimed to have a mass 6 times that 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 an orbital period of 270 days. However, subsequent studies using
Doppler spectroscopy
Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in t ...
failed to detect the
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 ...
variations that would be expected if such a planet was orbiting this small star.
The claimants of VB 10b note that these Doppler measurements only rule out planets more massive than 3 times the mass of Jupiter, but this limit is only half the reported best-fit mass of the planet as originally claimed. The claims for this planet thus fall into a long history of claimed astrometric
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 ...
detections that were subsequently refuted.
By 2016, it was suspected that the asymmetric debris disk signal was mistaken for the long-period planet.
See also
*
List of least massive stars
This is a list of brown dwarfs. These are objects that have masses between heavy gas giants and low-mass stars. The first isolated brown dwarf discovered was Teide 1 in 1995. The first brown dwarf discovered orbiting a star was Gliese 229 B, al ...
*
List of stars named after people
Over the past few centuries, a small number of stars have been named after individual people. It is common in astronomy for objects to be given names, in accordance with accepted astronomical naming conventions. Most stars have not been given prope ...
References
External links
*
{{DEFAULTSORT:Vb 10
Aquila (constellation)
M-type main-sequence stars
Binary stars
Flare stars
0752
Aquilae, V1298
Hypothetical planetary systems
J19165762+0509021