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Sigma Tauri - Wikipedia

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Sigma Tauri
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Location of σ² Tauri (circled)
Constellation	Taurus
σ¹ Tau
Right ascension	04^h 39^m 09.22247^s^[1]
Declination	+15° 47′ 59.5345″^[1]
Apparent magnitude (V)	5.07^[2]
σ² Tau
Right ascension	04^h 39^m 16.50230^s^[1]
Declination	+15° 55′ 04.7029″^[1]
Apparent magnitude (V)	4.70^[3]
Characteristics
σ¹ Tau
Spectral type	A4m^[4]
U−B color index	0.190^[2]
B−V color index	0.146^[2]
σ² Tau
Spectral type	A5 Vn^[5]
U−B color index	+0.13^[3]
B−V color index	+0.14^[3]
Astrometry
σ¹ Tau
Radial velocity (R_v)	+26.1±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 (45 ± 2 pc)
Absolute magnitude (M_V)	1.73^[2]
σ² Tau
Radial velocity (R_v)	+40.8±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 (47.7 ± 0.6 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 (K₁) (primary)	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)	56.5±7.1^[9] km/s
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	8,165±278^[10] K
Metallicity [Fe/H]	0.10±0.11^[12] dex
Rotational velocity (v sin i)	128^[5] km/s
Age	258^[10] Myr
Other designations
σ Tau, WDS J04393+1555
σ¹ Tau: 91 Tauri, BD+15° 665, HD 29479, HIP 21673, HR 1478, SAO 94051^[13]
σ² Tau: 92 Tauri, BD+15° 666, FK5 2345, HD 29488, HIP 21683, HR 1479, SAO 94054^[14]
Database references
SIMBAD	σ¹ Tau
	σ² Tau

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

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Iliev, I. Kh.; et al. (August 2006), "Abundance analysis of Am binaries and search for tidally driven abundance anomalies - II. HD861, HD18778, HD20320, HD29479, HD96528 and HD108651", Monthly Notices of the Royal Astronomical Society, 370 (2): 819–827, Bibcode:2006MNRAS.370..819I, doi:10.1111/j.1365-2966.2006.10513.x, S2CID 56133360.
^ ^a ^b ^c ^d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
^ ^a ^b Cowley, A.; et al. (1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
^ ^a ^b ^c ^d Royer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298.
^ ^a ^b de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
^ Pourbaix, D.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy and Astrophysics, 424 (2): 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088.
^ ^a ^b ^c ^d McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
^ ^a ^b Paunzen, E.; et al. (February 2013), "A photometric study of chemically peculiar stars with the STEREO satellites - II. Non-magnetic chemically peculiar stars", Monthly Notices of the Royal Astronomical Society, 429 (1): 119–125, arXiv:1211.1535, Bibcode:2013MNRAS.429..119P, doi:10.1093/mnras/sts318, S2CID 119231581.
^ ^a ^b ^c ^d ^e ^f ^g David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
^ ^a ^b Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics, 367 (Third ed.): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
^ Soubiran, C.; et al. (June 2010), "The PASTEL catalogue of stellar parameters", Astronomy and Astrophysics, 515: A111, arXiv:1004.1069, Bibcode:2010A&A...515A.111S, doi:10.1051/0004-6361/201014247, S2CID 118362423.
^ "sig01 Tau". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-06.{{cite web}}: CS1 maint: postscript (link)
^ "sig02 Tau". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-06.{{cite web}}: CS1 maint: postscript (link)
^ ^a ^b Burnham, Robert (2013), Burnham's Celestial Handbook, volume 3: An Observer's Guide to the Universe Beyond the Solar System, Dover Books on Astronomy, vol. 3, Courier Corporation, p. 1825, ISBN 978-0486318035
^ O'Meara, Stephen James (2016), Deep-Sky Companions: The Caldwell Objects, Cambridge University Press, p. 195, ISBN 978-1107083974.
^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 23 日 Archived 2014-02-26 at the Wayback Machine

Constellation of Taurus

Stars

Bayer	α (Aldebaran) β (Elnath) γ (Prima Hyadum) δ¹ (Secunda Hyadum) δ² δ³ ε (Ain) ζ (Tianguan) η (Alcyone) θ¹ θ² (Chamukuy) ι κ¹ κ² λ μ ν ξ ο π ρ σ¹ σ² τ υ φ χ ψ ω¹ ω²
Flamsteed	4 (s) 5 (f) 6 (t) 7 9 10 11 12 13 14 16 (Celaeno) 17 (Electra) 18 19 (Taygeta) 20 (Maia) 21 (Asterope) 22 (Asterope II) 23 (Merope) 24 26 27 (Atlas) 28 (Pleione) 29 (u) 30 (e) 31 32 33 36 37 (A¹) 39 (A²) 40 41 44 (p) 45 46 47 48 51 53 55 56 57 (h) 58 60 62 63 66 (r) 70 71 72 75 76 79 (b) 80 81 83 84 85 88 (d) 89 90 (c) 93 95 96 97 (i) 98 (k) 99 101 103 104 (m) 105 106 (l) 107 108 109 (n) 110 111 113 114 (o) 115 116 117 118 119 120 121 122 125 126 127 128 129 130 131 132 133 134 135 136 137 139 140 44 Eri 49 Eri
Variable	T Y Z RR RV RW RY RZ SU SV SZ TU UX UZ VY XX XZ AA AH BP CD CI CM CQ CT CU CW CY DD DF DG DH DI DL DM DN DO DQ DR DS EQ EU FN FS FU FV GG GI GK GV HK HL HU IK V410 V441 V471 V473 V479 V534 V624 V647 V650 V710 V711 V731 V766 V773 V774 V781 V807 V818 V819 V826 V827 V830 V833 V834 V836 V837 V892 V987 V1038 V1062 V1079 V1116 V1137 V1141 V1143 V1156 V1187 V1229 V1232 V1241 (WX Cas) V1298
HR	1023 1028 1039 1067 1085 1089 1102 1103 1110 1119 1137 1159 1172 1183 1185 1188 1201 1222 1224 1233 1237 1238 1253 1254 1257 1279 1280 1284 1295 1307 1310 1315 1349 1354 1358 1360 1370 1385 1400 1402 1403 1406 1413 1425 1427 1436 1442 1445 1446 1448 1455 1477 1480 1490 1512 1517 1554 1566 1575 1585 1633 1642 1741 1750 1755 1831 1847 1860 1878 1902 1921 1929 1954 1997 2013 2074
HD	21032 21585 23514 23712 24040 24368 24496 26292 27860 28086 28678 29627 29647 36112 37124 38263 38524 245134 285507
Other	2MASS J03552337+1133437 2MASS J04070752+1546457 2MASS J0441+2301 A0535+26 BD +24 692 Butterfly Star CoKu Tau/4 Elias 16 Elias 18 GD 71 Gliese 176 Haro 6-37 HBC 379 HH 30 HII 686 HII 1306 HII 1883 HII 3163 HP Tau/G2 Hubble I 4 HZ 9 IRAS 04239+2436 IRAS 04248+2612 IRAS 04325+2402 IRAS 04381+2540 K2-25 L1489 IRS L1527 L1551 IRS 5 L1521F-IRS MWC 480 PSR B0525+21 PSR B0540+23 PSR J0348+0432 PSR J0538+2813 Teide 1 TMR-1 TMC-1A WD 0346+246 WISE 0410+1502

Exoplanets	Aldebaran b ε Tauri b BD+20 594b HD 24040 b HD 37124 b c d Kojima-1Lb TOI-4603 b