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GRS 1915+105 or V1487 Aquilae is an X-ray binary star system containing a main sequence star and a black hole. Transfer of material from the star to the black hole generates a relativistic jet, making this a microquasar system. The jet exhibits apparent superluminal motion.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Aquila |
| Right ascension | 19h 15m 11.6s[2] |
| Declination | +10° 56′ 44″[2] |
| Characteristics | |
| Evolutionary stage | Microquasar[3] |
| Spectral type | KIII[4] |
| Astrometry | |
| Parallax (π) | 0.120 ± 0.009 mas[3] |
| Distance | 28,000 ly (8,600+2,000 −1,600[3] pc) |
| Details | |
| Black hole | |
| Mass | 12.4+2.0 −1.8[3][contradictory] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
It was discovered on August 15, 1992 by the WATCH all-sky monitor aboard Granat.[5] "GRS" stands for "GRANAT source", "1915" is the right ascension (19 hours and 15 minutes) and "105" reflects the approximate declination (10 degrees and 56 arcminutes). The near-infrared counterpart was determined by spectroscopic observations.[6]
The binary system lies 11,000 parsecs away[7] in Aquila. The black hole in GRS 1915+105 is 10 to 18 solar masses[8][contradictory]. The black hole rotates at least 950 times per second, giving it a spin parameter >0.82 (1.0 is the theoretical maximum).[9][10]
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In 1994, GRS 1915+105 became the first known galactic source that ejects material with apparent superluminal motion velocities.[11]
Observations with high resolution radio telescopes such as VLA, MERLIN, and VLBI show a bi-polar outflow of charged particles, which emit synchrotron radiation at radio frequencies. These studies have shown that the apparent superluminal motion is due to a relativistic effect known as relativistic aberration, where the intrinsic velocity of ejecta is actually about 90% the speed of light.[7]
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Repeat observations by the Chandra X-Ray Observatory 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.[12]
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