VB 10 or Van Biesbroeck's star is a very small and very dim red dwarf located in the constellation Aquila. It is part of a binary star 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 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 faci ...

. He found it while surveying the telescopic field of view of the high- proper-motion red dwarf Gliese 752 (Wolf 1055), for companions. Wolf 1055 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 **Ge ...

astronomer Max Wolf using similar astrophotographic techniques. It is designated VB 10 in the 1961 publication of Van Biesbroeck's star catalog. 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 obj ...

missed it even though its large parallax and large proper motion 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 astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it ...

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 ...

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 longitudes of the Sun and Moon differ by 180°). This means ...

. 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 manife ...

and actually be a star 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, 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 n ...

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 e ...

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 vers ...

'' 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 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 agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...

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, 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 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 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-thousandth t ...

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 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.

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