Sigma Serpentis

Sigma Serpentis, Latinized from σ Serpentis, is a star in the equatorial constellation Serpens. It is faintly visible to the naked eye with an apparent visual magnitude of +4.82.[2] Based upon an annual parallax shift of 36.67 mas as seen from Earth, it is located 89 light years from the Sun. The star is moving closer to the Sun with a radial velocity of −49 km/s.[5]

σ Serpentis
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Serpens
Right ascension 16h 22m 04.34753s[1]
Declination +01° 01′ 44.5534″[1]
Apparent magnitude (V) +4.82[2]
Characteristics
Spectral type F3 V[3] or A9 Ib/II[4]
U−B color index +0.025[2]
B−V color index +0.338[2]
Astrometry
Radial velocity (Rv)−49.3±0.9[5] km/s
Proper motion (μ) RA: −158.40[1] mas/yr
Dec.: +49.56[1] mas/yr
Parallax (π)36.67 ± 0.33[1] mas
Distance88.9 ± 0.8 ly
(27.3 ± 0.2 pc)
Absolute magnitude (MV)+2.63[6]
Details
Mass1.58±0.01[7] M☉
Luminosity7.7[7] L☉
Surface gravity (log g)4.05[6] cgs
Temperature6,952[8] K
Metallicity [Fe/H]−0.01[8] dex
Rotational velocity (v sin i)77.7[6] km/s
Age1.15±0.10[8] Gyr
Other designations
σ Ser, 50 Serpentis, BD+01° 3215, FK5 1427, HD 147449, HIP 80179, HR 6093, SAO 121540[9]
Database references
SIMBADdata

Barry (1970) assigned this star a stellar classification of F3 V,[3] indicating an ordinary F-type main-sequence star. However, Houk and Swift (1999) classified it as A9 Ib/II,[4] suggesting instead that this is an evolved F-type bright giant/supergiant. It is about one billion[8] years old and is spinning with a projected rotational velocity of 77.7 km/s.[6] The star has an estimated 1.58[7] times the mass of the Sun and is radiating 7.7[7] times the Sun's luminosity from its photosphere at an effective temperature of 6,952 K.[8]

References
  1. 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.
  2. Cousins, A. W. J. (1984), "Standardisation of broad band photometry of equatorial standards", South Africa Astronomical Observatory Circular, 8: 59–67, Bibcode:1984SAAOC...8...59C.
  3. Barry, Don C. (January 1970), "Spectral Classification of a and F Stars", Astrophysical Journal Supplement, 19: 281, Bibcode:1970ApJS...19..281B, doi:10.1086/190209.
  4. Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, Ann Arbor: Dep. Astron., Univ. Michigan, 5, Bibcode:1999MSS...C05....0H.
  5. 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, A61.
  6. Paunzen, E.; et al. (July 2014), "Investigating the possible connection between λ Bootis stars and intermediate Population II type stars", Astronomy & Astrophysics, 567: 8, arXiv:1406.3936, Bibcode:2014A&A...567A..67P, doi:10.1051/0004-6361/201423817, A67.
  7. Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691.
  8. Pace, G. (March 2013), "Chromospheric activity as age indicator. An L-shaped chromospheric-activity versus age diagram", Astronomy & Astrophysics, 551: 4, arXiv:1301.5651, Bibcode:2013A&A...551L...8P, doi:10.1051/0004-6361/201220364, L8.
  9. "sig Ser". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-10-20.
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