Tau1 Serpentis

Tau1 Serpentis, Latinized from τ1 Serpentis, is a single[9] star in the Caput (Head) segment of the equatorial constellation of Serpens. It is a red hued star that is dimly visible to the naked eye with an apparent visual magnitude of 5.16.[2] Based upon parallax measurements, this star is located at a distance of approximately 990 light years from the Sun,[1] while it is drifting closer with a radial velocity of −16.5 km/s.[2]

For other stars with this Bayer designation, see Tau Serpentis.
τ1 Serpentis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Serpens
Right ascension 15h 25m 47.39664s[1]
Declination +15° 25′ 40.9307″[1]
Apparent magnitude (V) 5.16[2] (5.13 to 5.20)[3]
Characteristics
Evolutionary stage AGB[4]
Spectral type M1III[5]
U−B color index +1.95[6]
B−V color index +1.650±0.006[2]
R−I color index +1.04[6]
Astrometry
Radial velocity (Rv)−16.51±0.23[2] km/s
Proper motion (μ) RA: −12.467[1] mas/yr
Dec.: −7.740[1] mas/yr
Parallax (π)3.3030 ± 0.1988[1] mas
Distance990 ± 60 ly
(300 ± 20 pc)
Absolute magnitude (MV)−1.45[2]
Details
Radius99+7
−14[1] R☉
Luminosity2,158±149[1] L☉
Surface gravity (log g)1.07±0.18[7] cgs
Temperature3,954+309
−132[1] K
Metallicity [Fe/H]0.05±0.06[7] dex
Other designations
τ1 Ser, 9 Serpentis, NSV 7074, BD+15°2858, FK5 570, GC 20740, HD 137471, HIP 75530, HR 5739, SAO 101545[8]
Database references
SIMBADdata

This object is an aging red giant star, currently on the asymptotic giant branch,[4] with a stellar classification of M1III.[5] Having exhausted the supply of hydrogen at its core, it has cooled and expanded until it now has around 99[1] times the girth of the Sun.[1] It is a suspected variable star with a brightness that has been measured varying from magnitude 5.13 down to 5.20.[3] The star is radiating 2,158[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3,954 K.[1]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  3. Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  4. Eggen, Olin J. (July 1992), "Asymptotic giant branch stars near the sun", Astronomical Journal, 104 (1): 275–313, Bibcode:1992AJ....104..275E, doi:10.1086/116239.
  5. Cenarro, A. J.; et al. (July 2009), "Mg and TiO spectral features at the near-IR: spectrophotometric index definitions and empirical calibrations", Monthly Notices of the Royal Astronomical Society, 396 (4): 1895–1914, arXiv:0903.4835, Bibcode:2009MNRAS.396.1895C, doi:10.1111/j.1365-2966.2009.14839.x, S2CID 15729759.
  6. Hoffleit, D.; Warren, Jr., W. H., "HR 5739", The Bright Star Catalogue (5th Revised ed.), retrieved 2019-10-17.
  7. Prugniel, P.; et al. (2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics, 531: A165, arXiv:1104.4952, Bibcode:2011A&A...531A.165P, doi:10.1051/0004-6361/201116769, S2CID 54940439.
  8. "tau01 Ser". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-17.
  9. 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.
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