GRS 1915+105 or V1487 Aquilae is an

X-ray binary X-ray binaries are a class of binary stars that are luminous in X-rays. The X-rays are produced by matter falling from one component, called the ''donor'' (usually a relatively normal star), to the other component, called the ''accretor'', which ...

star system which features a regular star and a

black hole A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...

. It was discovered on August 15, 1992 by the WATCH all-sky monitor aboard

Granat The International Astrophysical Observatory "GRANAT" (usually known as Granat; russian: Гранат, lit. ''pomegranate''), was a Soviet (later Russian) space observatory developed in collaboration with France, Denmark and Bulgaria. It was launc ...

. "GRS" stands for "GRANAT source", "1915" is the

right ascension Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the earth. When paired w ...

(19 hours and 15 minutes) and "105" reflects the approximate

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the ...

(10 degrees and 56 arcminutes). The near-infrared counterpart was confirmed by spectroscopic observations. The binary system lies 11,000

parsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and ...

s away in Aquila. GRS 1915+105 is the heaviest of the stellar black holes so far known in the

Milky Way Galaxy 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 eye. ...

, with 10 to 18 times the

mass of the Sun The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...

. It is also a

microquasar A microquasar, the smaller version of a quasar, is a compact region surrounding a stellar black hole with a mass several times that of its companion star. The matter being pulled from the companion star forms an accretion disk around the black hol ...

, and it appears that the black hole rotates at least 950 times per second, close to the maximum of 1,150 times per second, with a spin parameter value between 0.82 and 1.00 (maximum possible value).

Galactic superluminal source

In 1994, GRS 1915+105 became the first known galactic source that ejects material with apparent

superluminal motion In astronomy, superluminal motion is the apparently faster-than-light motion seen in some radio galaxies, BL Lac objects, quasars, blazars and recently also in some galactic sources called microquasars. Bursts of energy moving out along the rel ...

velocities. Observations with high resolution radio telescopes such as

VLA VLA or vla may refer to: Organizations * Vermont Library Association, professional organization for librarians from Vermont * Veterinary Laboratories Agency, a UK government agency for researching animal and public health * Victoria Legal Aid, an ...

MERLIN Merlin ( cy, Myrddin, kw, Marzhin, br, Merzhin) is a mythical figure prominently featured in the legend of King Arthur and best known as a mage, with several other main roles. His usual depiction, based on an amalgamation of historic and le ...

, and

VLBI Very-long-baseline interferometry (VLBI) is a type of astronomical interferometry used in radio astronomy. In VLBI a signal from an astronomical radio source, such as a quasar, is collected at multiple radio telescopes on Earth or in space. T ...

show a bi-polar outflow of charged particles, which emit

synchrotron radiation Synchrotron radiation (also known as magnetobremsstrahlung radiation) is the electromagnetic radiation emitted when relativistic charged particles are subject to an acceleration perpendicular to their velocity (). It is produced artificially in ...

at radio frequencies. These studies have shown that the apparent superluminal motion is due to a relativistic effect known as

relativistic aberration Relativistic aberration is the relativistic version of aberration of light, including relativistic corrections that become significant for observers who move with velocities close to the speed of light. It is described by Einstein's special theory ...

, where the intrinsic velocity of ejecta is actually about 90% the speed of light.

Growth regulation

Repeat observations by the

Chandra X-Ray Observatory The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space telescope launched aboard the during STS-93 by NASA on July 23, 1999. Chandra is sensitive to X-ray sources 1 ...

over the period of a decade have revealed what may be a mechanism for self-regulation of the rate of growth of GRS 1915+105. The jet of materials being ejected is occasionally choked off by a hot wind blowing off the accretion disk. The wind deprives the jet of materials needed to sustain it. When the wind dies down, the jet returns.

References

External links

A Very Massive Stellar Black Hole in the Milky Way Galaxy
November 28, 2001 (ESO)
Image V1487 Aquilae

O maior buraco negro estelar da Via Láctea (The biggest stellar black hole of the Milky Way)
- in Portuguese.

The micro quasar GRS 1915+105
INTEGRAL Science Data Centre {{DEFAULTSORT:GRS 1915+105 X-ray binaries Aquila (constellation) Microquasars Aquilae, V1487 K-type giants

Galactic superluminal source

Growth regulation

See also

References

External links