GS 2000+25

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.

GS 2000+25

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]

See also

• List of nearest black holes