HD 118889

HD 118889 is a binary star system in the northern constellation of Boötes. It is faintly visible to the naked eye as a point of light with an apparent visual magnitude of 5.57.^[1] The system is located at a distance of approximately 196 light years from the Sun based on stellar parallax,^[2] but is drifting closer with a radial velocity of −26 km/s.^[8]

HD 118889

Observation data Epoch J2000      Equinox J2000
Constellation	Boötes[1]
Right ascension	13h 39m 34.61613s[2]
Declination	+10° 44′ 46.5827″[2]
Apparent magnitude (V)	5.57[1] (6.35 + 6.47)‍[3]
Characteristics
Evolutionary stage	Main sequence[4][5]
Spectral type	F0V[6]
U−B color index	+0.045[7]
B−V color index	+0.33[7]
Astrometry
Radial velocity (Rv)	−25.9±1.9[8] km/s
Proper motion (μ)	RA: −114.96[2] mas/yr Dec.: −11.74[2] mas/yr
Parallax (π)	16.67±0.58 mas[2]
Distance	196 ± 7 ly (60 ± 2 pc)
Absolute magnitude (MV)	+2.40[9]
Orbit[10]
Period (P)	22.460±0.019 yr
Semi-major axis (a)	0.19983±0.00055″
Eccentricity (e)	0.5450±0.0022
Inclination (i)	43.50±0.40°
Longitude of the node (Ω)	34.58±0.52°
Periastron epoch (T)	B 1929.850±0.024
Argument of periastron (ω) (secondary)	359.93±0.79°
Details
A
Mass	1.59[11] M☉
B
Mass	1.55[11] M☉
Other designations
BD+11°2589, HD 118889, HIP 66640, HR 5138, SAO 100654, ADS 8987, WDS 13396+1045, BU 612
Database references
SIMBAD	data

The binary components of this system were first measured by S. W. Burnham in 1878 and it was given the discovery code BU 612.^[12] The pair are orbiting each other with a period of 22.46 years with an eccentricity (ovalness) of 0.545. The primary component is magnitude 6.35, with the secondary slightly fainter at magnitude 6.47.^[3]

A third star, 3.5″ away, is a 12th-magnitude common-proper-motion companion. Any orbit would take over a thousand years.^[11]