Upsilon Serpentis

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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]
Spectral type A3 V[3]
U−B color index +0.09[2]
B−V color index +0.10[2]
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
Distance 250 ± 20 ly
(77 ± 5 pc)
Mass 2.9±0.23[5] M
Radius 2.2[6] R
Luminosity 23[7] L
Surface gravity (log g) 4.0±0.14[5] cgs
Temperature 8,917±303[5] K
Rotational velocity (v sin i) 133[8] km/s
Age 403+70
[5] Myr
Other designations
υ Ser, 31 Ser, BD+14° 2939, HD 141187, HIP 77336, HR 5870, SAO 101739.[9]
Database references

Upsilon Serpentis (υ Ser, 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.[10]

This is an A-type main sequence star with a stellar classification of A3 V.[3] It has an estimated 2.9[5] times the mass of the Sun and around 2.2[6] times the Sun's radius. With an age of 403[5] million years, it has a high rate of spin with a projected rotational velocity of 133 km/s.[8] It is radiating 23[7] times the solar luminosity from its photosphere at an effective temperature of 8,917 K.[5]

Upsilon Serpentis is a suspected astrometric binary,[11] 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.[12]


  1. ^ a b c d e van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, 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 ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV data, SIMBAD, Bibcode:1986EgUBV........0M. 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 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, Bibcode:2012A&A...546A..61D, arXiv:1208.3048Freely accessible, doi:10.1051/0004-6361/201219219, A61. 
  5. ^ a b c d e f g Gullikson, Kevin; et al. (August 2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal, 152 (2): 13, Bibcode:2016AJ....152...40G, arXiv:1604.06456Freely accessible, doi:10.3847/0004-6256/152/2/40, 40. 
  6. ^ 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, Bibcode:2001A&A...367..521P, arXiv:astro-ph/0012289Freely accessible, doi:10.1051/0004-6361:20000451. 
  7. ^ 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, Bibcode:2012MNRAS.427..343M, arXiv:1208.2037Freely accessible, doi:10.1111/j.1365-2966.2012.21873.x. 
  8. ^ a b Royer, F.; et al. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, Bibcode:2007A&A...463..671R, arXiv:astro-ph/0610785Freely accessible, doi:10.1051/0004-6361:20065224. 
  9. ^ "phi Ser -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-03-23. 
  10. ^ Eggen, O. J. (October 1982), "The Hyades main sequence", Astrophysical Journal Supplement Series, 50: 221−239, Bibcode:1982ApJS...50..221E, doi:10.1086/190826. 
  11. ^ 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, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x. 
  12. ^ 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.