HD 120987

This article is about y Centauri and is not to be confused with γ (gamma) Centauri or Y Centauri.

HD 120987 (y Centauri or y Cen) is a star system located in the constellation Centaurus. HD 120987 is a quintuple star system located 50 pc (163 light years) from the Sun. The system has an apparent magnitude of 5.565.^[3] Based on the system's parallax, it is located some 172 light-years (52 parsecs) away.^[2]

HD 120987

Observation data Epoch J2000      Equinox J2000
Constellation	Centaurus[1]
Right ascension	13h 53m 32.76039s[2]
Declination	−35° 39′ 51.3200″[2]
Apparent magnitude (V)	5.565[3] (6.27 / 6.38)‍[4]
Characteristics
Spectral type	F4V (F0V + F1V)[5]
U−B color index	−0.03[6]
B−V color index	+0.44[6]
Astrometry
Radial velocity (Rv)	−8.00±7.40[7] km/s
Proper motion (μ)	RA: −83.39[2] mas/yr Dec.: −25.36[2] mas/yr
Parallax (π)	19.13±0.93 mas[2]
Distance	170 ± 8 ly (52 ± 3 pc)
Absolute magnitude (MV)	+1.84[1]
Orbit[4]
Period (P)	373.0 yr
Semi-major axis (a)	1.519″
Eccentricity (e)	0.775
Inclination (i)	74.2°
Longitude of the node (Ω)	112.3°
Periastron epoch (T)	B 1958.57
Argument of periastron (ω) (secondary)	90.7°
Details
HD 120987 A
Mass	1.56[8] M☉
HD 120987 B
Mass	1.53[8] M☉
Other designations
CD−35°9090, HD 120987, HIP 67819, HR 5222, SAO 204955[3]
Database references
SIMBAD	data

HD 120987 appears to be a single F-type star with the spectral classification F4V, but closer inspection reveals it to be two similar F-type main-sequence stars with spectral classifications of F0V and F1V, respectively.^[5] The two orbit each other every 373 years, and are separated by 1.519 arcseconds while taking a very eccentric orbit.^[4]