Upsilon Serpentis

Upsilon Serpentis, Latinized from υ Serpentis, is a star in the Serpens Caput section of the constellation Serpens. Based upon an annual parallax shift of 13.04 mas as seen from Earth, it is located around 250 light years from the Sun. The star is bright enough to be faintly visible to the naked eye, having an apparent visual magnitude of +5.70.[2] It is a member of the Hyades group, a stream of stars that share a similar trajectory to the Hyades cluster.[11]

Upsilon Serpentis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Serpens
Right ascension  15h 47m 17.31882s[1]
Declination +14° 06′ 55.2617″[1]
Apparent magnitude (V) +5.70[2]
Characteristics
Spectral type A3 V[3]
U−B color index +0.09[2]
B−V color index +0.10[2]
Astrometry
Radial velocity (Rv)−34.2±2.9[4] km/s
Proper motion (μ) RA: −55.49[1] mas/yr
Dec.: +32.42[1] mas/yr
Parallax (π)13.04 ± 0.84[1] mas
Distance250 ± 20 ly
(77 ± 5 pc)
Absolute magnitude (MV)+1.30[5]
Details
Mass2.9±0.23[6] M☉
Radius2.2[7] R☉
Luminosity23[8] L☉
Surface gravity (log g)4.0±0.14[6] cgs
Temperature8,917±303[6] K
Rotational velocity (v sin i)133[9] km/s
Age403+70
−75[6] Myr
Other designations
υ Ser, 31 Serpentis, BD+14° 2939, HD 141187, HIP 77336, HR 5870, SAO 101739[10] υ Ser, 31 Ser, BD+14° 2939, HD 141187, HIP 77336, HR 5870, SAO 101739.
Database references
SIMBADdata

This is an A-type main sequence star with a stellar classification of A3 V.[3] It has an estimated 2.9[6] times the mass of the Sun and around 2.2[7] times the Sun's radius. With an age of 403[6] million years, it has a high rate of spin with a projected rotational velocity of 133 km/s.[9] It is radiating 23[8] times the solar luminosity from its photosphere at an effective temperature of 8,917 K.[6]

Upsilon Serpentis is a suspected astrometric binary,[12] which means an undetected companion is perturbing the motion of the visible star. An X-ray emission has been detected from this system with a luminosity of 247.8×1020 W. This may be coming from the companion, since A-type stars are not expected to emit X-rays.[13]

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. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.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. Cowley, A.; et al. (April 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.
  4. 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.
  5. 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.
  6. Gullikson, Kevin; et al. (August 2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal, 152 (2): 13, arXiv:1604.06456, Bibcode:2016AJ....152...40G, doi:10.3847/0004-6256/152/2/40, 40.
  7. 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.
  8. 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.
  9. 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.
  10. "phi Ser". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-03-23.
  11. Eggen, O. J. (October 1982), "The Hyades main sequence", Astrophysical Journal Supplement Series, 50: 221–239, Bibcode:1982ApJS...50..221E, doi:10.1086/190826.
  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. Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics, 475 (2): 677–684, Bibcode:2007A&A...475..677S, doi:10.1051/0004-6361:20077429.
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