Omicron Serpentis

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Omicron Serpentis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Serpens
Right ascension 17h 41m 24.87286s[1]
Declination −12° 52′ 31.1086″[1]
Apparent magnitude (V) 4.26[2]
Spectral type A2 Va[3]
U−B color index +0.08[2]
B−V color index +0.07[2]
Variable type δ Sct[4]
Radial velocity (Rv)−30.2±1.2[5] km/s
Proper motion (μ) RA: −72.90[1] mas/yr
Dec.: −55.55[1] mas/yr
Parallax (π)18.83 ± 0.25[1] mas
Distance173 ± 2 ly
(53.1 ± 0.7 pc)
Absolute magnitude (MV)+0.760[6]
Mass2.13[7] M
Radius2.2[8] R
Luminosity42.6[9] L
Surface gravity (log g)3.82±0.14[7] cgs
Temperature8,972±305[7] K
Rotational velocity (v sin i)112.6±1.2[10] km/s
Age518[7] Myr
Other designations
ο Ser, 56 Ser, BD−12° 4808, FK5 3405, HD 160613, HIP 86565, HR 6581, SAO 160747.[11]
Database references

Omicron Serpentis (ο Ser, ο Serpentis) is a solitary[12] star in the Serpens Cauda (tail) section of the equatorial constellation Serpens. Based upon an annual parallax shift of 18.83 mas as seen from Earth,[1] it is located around 173 light years from the Sun. The star is visible to the naked eye with a base apparent visual magnitude of +4.26.[2]

This is a white-hued A-type main sequence star with a stellar classification of A2 Va.[3] It is located on the lower instability strip[6] and is classified as a Delta Scuti type variable star. The apparent magnitude of the star varies in the range 4.26−4.27 with a period of 76 minutes, or 0.053 days.[6][13]

The star has an estimated 2.13[7] times the mass of the Sun and about 2.2[8] times the Sun's radius. It is about half a billion[7] years old and is spinning with a projected rotational velocity of 112.6 km/s.[10] Omicron Serpentis is radiating 42.6[9] times the solar luminosity from its photosphere at an effective temperature of 8,972 K.[7]


  1. ^ a b c d e f 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. ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV data, SIMBAD, Bibcode:1986EgUBV........0M.
  3. ^ a b Houk, N. (1988), Michigan catalogue of two-dimensional spectral types for the HD stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan,
  4. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009), "General Catalogue of Variable Stars (Samus+ 2007-2013)", VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S, 1, Bibcode:2009yCat....102025S.
  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. ^ a b c Garcia, J. R.; et al. (February 1995), "A catalogue of variable stars in the lower instability strip", Astronomy and Astrophysics Supplement, 109: 201–262, Bibcode:1995A&AS..109..201G.
  7. ^ 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.
  8. ^ a b Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (3rd ed.), 367: 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  9. ^ a b 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.
  10. ^ a b Díaz, C. G.; et al. (July 2011), "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum", Astronomy & Astrophysics, 531: A143, arXiv:1012.4858, Bibcode:2011A&A...531A.143D, doi:10.1051/0004-6361/201016386.
  11. ^ "omi Ser". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-03-23.
  12. ^ 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.
  13. ^ Chang, S.-W.; et al. (2013), "Statistical Properties of Galactic δ Scuti Stars: Revisited", The Astronomical Journal, 145 (5): 132, arXiv:1303.1031, Bibcode:2013AJ....145..132C, doi:10.1088/0004-6256/145/5/132.