Tau2 Lupi

Tau² Lupi, Latinized from τ² Lup, is a binary star^[3] system in the constellation Lupus. It is visible to the naked eye with a combined apparent visual magnitude of 4.34.^[2] Based upon an annual parallax shift of 10.22^[1] mas as seen from Earth, it is located around 319 light years from the Sun. The two components orbit each other with a period of 26.2 years and a high eccentricity of 0.94.^[6] The brighter component is a magnitude 4.93 subgiant star with a stellar classification of F4 IV. Its companion is an A-type star with visual magnitude 5.55 and class A7:.^[3]

For other stars with this Bayer designation, see τ Lupi.

Tau² Lupi

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Lupus
Right ascension	14h 26m 10.81378s[1]
Declination	−45° 22′ 45.4023″[1]
Apparent magnitude (V)	4.34[2] (4.93 + 5.55)[3]
Characteristics
Spectral type	F4 IV + A7:[3]
U−B color index	+0.16[2]
B−V color index	+0.43[2]
Astrometry
Radial velocity (Rv)	−0.60±1.60[4] km/s
Proper motion (μ)	RA: +14.62[1] mas/yr Dec.: −7.33[1] mas/yr
Parallax (π)	10.22±0.31 mas[1]
Distance	319 ± 10 ly (98 ± 3 pc)
Absolute magnitude (MV)	−0.62[5]
Orbit[6]
Period (P)	26.2 yr
Semi-major axis (a)	0.125″
Eccentricity (e)	0.94
Inclination (i)	56.0°
Longitude of the node (Ω)	175.7°
Periastron epoch (T)	1969.1
Argument of periastron (ω) (secondary)	191.0°
Details
Luminosity	150[5] L☉
Rotational velocity (v sin i)	0[7] km/s
Other designations
τ2 Lup, CD−44°9323, HD 126354, HIP 70576, HR 5396, SAO 224920[8]
Database references
SIMBAD	data