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 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 ...

9 ''Gliese (GJ) 752 A''. The secondary star is the dim

17 ''Gliese (GJ) 752 B'', more commonly referred to as ''

VB 10 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 k ...

''. This stellar pair form a

binary star system 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 ...

separated by about 74 arc seconds (~434 AU). This system is also known for its high proper motion of about 1 arc second a year. Component A has one known exoplanet. The name and number are from the '' Catalogue of Nearby Stars'', published by German astronomer

Wilhelm Gliese Wilhelm Gliese (, English ; 21 June 1915 – 12 June 1993) was a German astronomer who specialized in the study and cataloging of nearby stars. Life Gliese was born in Goldberg, now in Polish Silesia, the son of judge Wilhelm Gliese. He wor ...

in 1969.

Interior dynamics of the Gliese 752 stars

Before 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 ...

observation of ''Gliese 752'' system, astronomers thought magnetic fields in stars required the same dynamo process that creates magnetic fields on 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 ...

. In the classic solar model heat generated 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 manife ...

reactions at the star's center escapes through a radiative zone just outside the core. The heat travels from the radiative core to the star's surface through a convection zone. In this region, heat bubbles to the surface by motions similar to boiling in a pot of water.

Dynamo "Dynamo Electric Machine" (end view, partly section, ) A dynamo is an electrical generator that creates direct current using a commutator. Dynamos were the first electrical generators capable of delivering power for industry, and the foundati ...

s, which accelerate

electrons The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no ...

to create magnetic forces, operate when the interior of a star rotates faster than its surface. Recent studies of the

indicate its convection zone rotates at nearly the same rate at all depths. This means the solar dynamo must operate in the more rapidly rotating radiative core just below the

convective 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 convec ...

zone.

Gliese 752 A characteristics

The primary star, also known as ''Wolf 1055'', is a type M2.5 red dwarf with about half the size and mass as the

and considerably cooler at 3354 K. This star was first observed to be a high proper motion star by the German astronomer Max Wolf with his pioneering use of

astrophotography Astrophotography, also known as astronomical imaging, is the photography or imaging of astronomical objects, celestial events, or areas of the night sky. The first photograph of an astronomical object (the Moon) was taken in 1840, but it was no ...

. He added this star to his extensive catalog of such stars in 1919. It is a variable star with the

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 ...

catalog name ''V1428 Aquilae''. It is a '' BY Draconis'' type

subject to flare events.

Planetary system

In August 2018, a group of scientist using measurements taken from the CARMENES spectrograph, on the Calar Alto Observatory located in Spain, announced they had detected a planet orbiting the larger of the stars, HD 180617 (Gliese 752 A). The measurements indicated the presence of a planet with a minimum mass comparable to Neptune on an orbit partly located within the habitable zone.

Gliese 752 B characteristics

Gliese 752 was not known to be a binary star system until the discovery of a small dim secondary star by

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 ...

in 1944. This star is identified as ''

'' in

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 ...

. This star is notable for its very low mass. At .08 solar mass it is near the lower mass limit for a star. It is also quite small at 10% of the solar radius. This star is a type M8V red dwarf. This star is also known for its very low luminosity, with an

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, due to its very cool surface temperature of only 2600°K. It is a

with the

catalog name ''V1298 Aquilae''. This star 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

also subject to flare events. It shares the large proper motion, along with the tendency to

flare A flare, also sometimes called a fusée, fusee, or bengala in some Latin-speaking countries, is a type of pyrotechnic that produces a bright light or intense heat without an explosion. Flares are used for distress signaling, illumination, ...

, with the primary star. In 2009 the discovery of the

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 ...

, '' VB 10b'', was announced in orbit around this star. However a subsequent spectrographic survey failed to confirm the presence of any large planets in orbit around this star.

Notes

References

External links

{{DEFAULTSORT:Gliese 752 Aquila (constellation) 094761 M-type main-sequence stars Flare stars 180617 0752 Binary stars Planetary systems with one confirmed planet Durchmusterung objects Aquilae, V1428/V1298 BY Draconis variables