Tau Centauri

Not to be confused with T Centauri.

Tau Centauri, Latinized from τ Centauri, is a solitary^[11] star in the southern constellation of Centaurus. It is visible to the naked eye with an apparent visual magnitude of +3.86.^[2] The distance to this star, based upon an annual parallax shift of 24.85 mas,^[1] is 131 light years. It makes a star system with Gamma Centauri at 98% probability, both separated by 1.7 ly (0.53 pc).^[12]

τ Centauri

Location of τ Centauri (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Centaurus
Right ascension	12h 37m 42.16377s[1]
Declination	−48° 32′ 28.6899″[1]
Apparent magnitude (V)	+3.86[2]
Characteristics
Spectral type	A0 V[3] or A1 IVnn[4]
U−B color index	+0.04[2]
B−V color index	+0.06[2]
Astrometry
Radial velocity (Rv)	+5.5±2.3[5] km/s
Proper motion (μ)	RA: −186.26[1] mas/yr Dec.: −6.01[1] mas/yr
Parallax (π)	24.85±0.53 mas[1]
Distance	131 ± 3 ly (40.2 ± 0.9 pc)
Absolute magnitude (MV)	+0.83[6]
Details
Mass	2.31[7] M☉
Radius	2.7[8] R☉
Luminosity	39[8] L☉
Surface gravity (log g)	4.02±0.14[7] cgs
Temperature	10,533±358[7] K
Rotational velocity (v sin i)	296.8±3.8[9] km/s
Age	132[7] Myr
Other designations
τ Cen, CD−47°7745, HD 109787, HIP 61622, HR 4802, SAO 223560[10]
Database references
SIMBAD	data

This is an A-type star with stellar classifications of A0 V^[3] or A1 IVnn,^[4] indicating it may be a main sequence star or a more evolved subgiant star. It is around 132 million years old^[7] and is spinning rapidly with a projected rotational velocity of 296.8 km/s.^[9] This is giving the star an oblate shape, with an estimated equatorial girth that is 30% larger than the polar radius.^[13] The star has an estimated 2.3 times the mass of the Sun^[7] and 2.7 times the Sun's radius.^[8]