Sigma2 Tauri

Sigma² Tauri (σ² Tauri) is the Bayer designation for a white-hued star in the zodiac constellation of Taurus. It has an apparent visual magnitude of +4.70,^[2] which indicates it is visible to the naked eye. Based upon parallax measurements, σ² Tauri is about 156 light-years distant.

Sigma2 Tauri

Location of σ2 Tauri (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Taurus
Right ascension	04h 39m 16.50230s[1]
Declination	+15° 55′ 04.7029″[1]
Apparent magnitude (V)	4.70[2]
Characteristics
Spectral type	A5 Vn[3]
U−B color index	+0.13[2]
B−V color index	+0.14[2]
Astrometry
Radial velocity (Rv)	+40.8±1.2[4] km/s
Proper motion (μ)	RA: +83.17[1] mas/yr Dec.: −20.97[1] mas/yr
Parallax (π)	20.97±0.27 mas[1]
Distance	156 ± 2 ly (47.7 ± 0.6 pc)
Details
Mass	1.71[5] M☉
Radius	1.9[6] R☉
Luminosity	22.5[7] L☉
Surface gravity (log g)	3.96[5] cgs
Temperature	8,165±278[5] K
Metallicity [Fe/H]	0.10±0.11[8] dex
Rotational velocity (v sin i)	128[3] km/s
Age	258[5] Myr
Other designations
92 Tauri, BD+15°666, FK5 2345, HD 29488, HIP 21683, HR 1479, SAO 94054, WDS J04393+1555A[9]
Database references
SIMBAD	data

σ² Tauri is a solitary^[10] A-type main sequence star with a stellar classification of A5 Vn.^[3] The 'n' suffix indicates the lines are "nebulous" due to rapid rotation, and indeed it is spinning with a projected rotational velocity of 128 km/s.^[3] The star is an estimated 258^[5] million years old, with 1.7^[5] times the mass of the Sun. It is radiating 22.5^[7] times the Sun's luminosity from its photosphere at an effective temperature of around 8,165 K.^[5] The star is considered a member of the Hyades cluster.^[6]

In Chinese astronomy, σ² Tauri is called 附耳, Pinyin: Fùěr, meaning Whisper, because this star is marking itself and stands alone in the Whisper asterism of the Net mansion (see: Chinese constellation).^[11]