GS 2000+25
Star in the constellation Vulpecula
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GS 2000+25 is an X-ray binary system in the constellation Vulpecula, consisting of a late K-type star and a black hole. It is also an X-ray nova.
 Near-infrared (I band) light curves for QZ Vulpeculae, adapted from Chevalier and Ilovaisky (1993).[1] The data were collected over a 10 night period in July 1991. Data collected on different nights are plotted with different colors. The shape of the light curve changed over a period of approximately two days, leading to different shapes on even or odd numbered days. | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Vulpecula |
| Right ascension | 20h 02m 49.58s[2] |
| Declination | +25° 14′ 11.3″[2] |
| Apparent magnitude (V) | 18.2[2] |
| Characteristics | |
| Spectral type | Black hole + K3-6 V[3] |
| Astrometry | |
| Distance | 8800 ± 2300 ly (2700 ± 700[4] pc) |
| Orbit | |
| Period (P) | 8.26 hr[2] |
| Details | |
| Black hole | |
| Mass | 7.2–7.8[3] M☉ |
| Other designations | |
| Nova Vul 1988, INTREF 1007, QZ Vul[5] | |
| Database references | |
| SIMBAD | data |
Fumiyoshi Makino and the Ginga satellite team discovered GS 2000+25, in April of 1988.[6] A few days later a star, variable in visible light, was identified at its position.[7] It received its variable star designation, QZ Vulpeculae, in 1989.[8]
Properties
Because the black hole is more massive than the companion star, it is the primary of the system. The black hole has a mass of about 5 solar masses while the companion has a mass of about 0.5 solar masses. Because the companion star has a low mass, the system is a low-mass X-ray binary.[9]
