Sigma Tauri

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Template:Short description

Sigma Tauri
Template:Location mark
Location of σ2 Tauri (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Taurus
σ1 Tau
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 5.07[2]
σ2 Tau
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 4.70[3]
Characteristics
σ1 Tau
Spectral type A4m[4]
U−B Template:Engvar 0.190[2]
B−V Template:Engvar 0.146[2]
σ2 Tau
Spectral type A5 Vn[5]
U−B Template:Engvar +0.13[3]
B−V Template:Engvar +0.14[3]
Astrometry
σ1 Tau
Radial velocity (Rv)Template:Val[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]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)1.73[2]
σ2 Tau
Radial velocity (Rv)Template:Val[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]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Orbit[7]
Primaryσ1 Tau A
Companionσ1 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 (K1)
(primary)		7.9 km/s
Details
σ1 Tau
Mass1.94[2] Template:Solar mass
Luminosity14.7[8] Template:Solar luminosity
Surface gravity (log g)4.08[2] cgs
Temperature8,470[2] K
Rotational velocity (v sin i)Template:Val[9] km/s
σ2 Tau
Mass1.71[10] Template:Solar mass
Radius1.9[11] Template:Solar radius
Luminosity22.5[8] Template:Solar luminosity
Surface gravity (log g)3.96[10] cgs
TemperatureTemplate:Val[10] K
Metallicity [Fe/H]Template:Val[12] dex
Rotational velocity (v sin i)128[5] km/s
Age258[10] Myr
Other designations
Template:Odlist
σ1 Tau: Template:Odlist[13]
σ2 Tau: Template:Odlist[14]
Database references
SIMBADσ1 Tau
σ2 Tau

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Sigma Tauri (σ Tauri) is the Bayer designation for a pair of white-hued stars in the zodiac constellation of Taurus. The system is a visual double star, whose components are designated σ1 Tauri and σ2 Tauri, with the latter being the more northerly star.[15] The two are separated by 7.2[16] arcminutes on the sky and can be readily split with a pair of binoculars.[15] They have apparent visual magnitudes of +5.07[2] and +4.70,[3] respectively, which indicates they are both visible to the naked eye. Based upon parallax measurements, σ1 Tauri is about 147 light years from the Sun, while σ2 Tauri is 156 light years distant.

σ1 Tauri is a single-lined spectroscopic binary star system with an orbital period of 38.951 days and an eccentricity of 0.15. The visible component is an Am star with a stellar classification of A4m,[4] indicating it is chemically peculiar A-type star. It is spinning with a projected rotational velocity of 56.5 km/s.[9] The star has 1.9[2] times the mass of the Sun and is radiating 14.7[8] times the Sun's luminosity from its photosphere at an effective temperature of 8,470 K.[2] Although it lies in the general direction of the 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 a stellar classification of A5 Vn.[5] 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.[5] The star is an estimated 258[10] million years old, with 1.7[10] times the mass of the Sun. It is radiating 22.5[8] times the Sun's luminosity from its photosphere at an effective temperature of around 8,165 K.[10] The star is considered a member of the Hyades cluster.[11]

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).[18]

References

Template:Reflist

Template:Stars of Taurus

  1. ↑ a b c d e f g h i j Cite error: Invalid <ref> tag; no text was provided for refs named vanLeeuwen2007
  2. ↑ a b c d e f g h i j k Cite error: Invalid <ref> tag; no text was provided for refs named Iliev2006
  3. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named Johnson1966
  4. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Cowley1969
  5. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named Royer2007
  6. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named deBruijne2012
  7. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Pourbaiz2004
  8. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named Mcdonald2012
  9. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Paunzen2013
  10. ↑ a b c d e f g Cite error: Invalid <ref> tag; no text was provided for refs named David2015
  11. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named PasinettiFracassini2001
  12. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Soubiran2010
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named SIMBAD_01
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named SIMBAD_02
  15. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Burnham2013
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named OMeara2016
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Eggleton2008
  18. ↑ Template:In lang AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 23 日 Template:Webarchive
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