GRS 1915+105

GRS 1915+105
	; A near-infrared (K band) light curve for V1487 Aquilae, adapted from Neil et al. (2007)
Observation data; Epoch J2000.0 Equinox J2000.0
Constellation	Aquila
Right ascension	19h 15m 11.6s
Declination	+10° 56′ 44″
Characteristics
Evolutionary stage	Microquasar
Spectral type	KIII
Astrometry
Parallax (π)	0.120 ± 0.009 mas
Distance	28,000 ly ; (8,600+2,000; −1,600 pc)
Details
Black hole
Mass	12.4+2.0; −1.8 M☉
Other designations
	V1487 Aquilae, Granat 1915+105, Nova Aquilae 1992, Granat 1915+10, INTEGRAL1 112
Database references
SIMBAD	data

GRS 1915+105 or V1487 Aquilae is an X-ray binary star system which features a regular star and a black hole. It was discovered on August 15, 1992 by the WATCH all-sky monitor aboard Granat. "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 confirmed by spectroscopic observations. The binary system lies 11,000 parsecs away in Aquila. GRS 1915+105 is the heaviest of the stellar black holes so far known in the Milky Way Galaxy, with 10 to 18 times the mass of the Sun. It is also a microquasar, 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).

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