Star in the constellation Taurus
Sigma Tauri Location of σ
2 Tauri (circled)
Observation dataEpoch J2000.0 Equinox J2000.0 (ICRS ) Constellation Taurus σ1 Tau Right ascension 04h 39m 09.22247s [ 1] Declination +15° 47′ 59.5345″[ 1] Apparent magnitude (V)5.07[ 2] σ2 Tau Right ascension 04h 39m 16.50230s [ 1] Declination +15° 55′ 04.7029″[ 1] Apparent magnitude (V)4.70[ 3] Characteristics σ1 Tau Spectral type A4m[ 4] U−Bcolor index 0.190[ 2] B−Vcolor index 0.146[ 2] σ2 Tau Spectral type A5 Vn[ 5] U−Bcolor index +0.13[ 3] B−Vcolor index +0.14[ 3] Astrometry σ1 Tau Radial velocity (Rv )± 10.0[ 6] km/s Proper motion (μ)RA: +41.91[ 1] mas /yr Dec.: −66.88[ 1] mas /yr Parallax (π)22.18± 0.93 mas [ 1] Distance 147 ± 6 ly pc ) Absolute magnitude (MV )1.73[ 2] σ2 Tau Radial velocity (Rv )± 1.2[ 6] 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 pc ) Orbit [ 7] Primary σ1 Tau A Companion σ1 Tau B Period (P)38.951 d Eccentricity (e)0.15 Longitude of the node (Ω)82° Periastron epoch (T)2443094.319 JD Semi-amplitude 1 )7.9 km/s Details σ1 Tau Mass 1.94[ 2] M ☉ Luminosity 14.7[ 8] L ☉ Surface gravity (log g )4.08[ 2] cgs Temperature 8,470[ 2] K Rotational velocity (v sin i )± 7.1[ 9] σ2 Tau Mass 1.71[ 10] M ☉ Radius 1.9[ 11] R ☉ Luminosity 22.5[ 8] L ☉ Surface gravity (log g )3.96[ 10] cgs Temperature ± 278[ 10] K Metallicity ± 0.11[ 12] dex Rotational velocity (v sin i )128[ 5] Age 258[ 10] Myr Other designations σ Tau ,WDS J04393+1555σ1 Tau :91 Tauri ,BD +15° 665HD 29479HIP 21673HR 1478SAO 94051[ 13] σ2 Tau :92 Tauri ,BD +15° 666FK5 2345HD 29488HIP 21683HR 1479SAO 94054[ 14] Database references SIMBAD σ1 Tau σ2 Tau
Sigma Tauri (σ Tauri) is theBayer designation for a pair of white-huedstars in thezodiac constellation ofTaurus . The system is a visualdouble star , whose components are designatedσ1 Tauri andσ2 Tauri , with the latter being the more northerly star.[ 15] [ 16] arcminutes on the sky and can be readily split with a pair of binoculars.[ 15] apparent visual magnitudes of +5.07[ 2] [ 3] 1 Tauri is about 147 light years from theSun , while σ2 Tauri is 156 light years distant.
σ1 Tauri is a single-linedspectroscopic binary star system with anorbital period of 38.951 days and aneccentricity of 0.15. The visible component is anAm star with astellar classification of A4m,[ 4] chemically peculiar A-type star . It is spinning with aprojected rotational velocity of 56.5 km/s.[ 9] [ 2] mass of the Sun and is radiating 14.7[ 8] Sun's luminosity from itsphotosphere at aneffective temperature of 8,470 K.[ 2] Hyades cluster , based on parallax measurements it has been excluded from the list of candidate members.[ 2]
σ2 Tauri is a solitary[ 17] A-type main sequence star with astellar classification of A5 Vn.[ 5] projected rotational velocity of 128 km/s.[ 5] [ 10] [ 10] mass of the Sun . It is radiating 22.5[ 8] Sun's luminosity from itsphotosphere at aneffective temperature of around 8,165 K.[ 10] Hyades cluster .[ 11]
InChinese astronomy , σ2 Tauri is called 附耳,Pinyin : Fùěr, meaningWhisper , because this star is marking itself and stands alone in theWhisper asterism of theNet mansion (see :Chinese constellation ).[ 18]
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