Tau2 Serpentis

Tau2 Serpentis, Latinized from τ2 Serpentis, is a star in the constellation of Serpens, located approximately 480 light-years from the Sun.[1] It is a challenge to view with the naked eye, having an apparent visual magnitude of 6.22.[2] The star is drifting closer with a radial velocity of −19 km/s.[2]

For other stars with this Bayer designation, see Tau Serpentis.
τ2 Serpentis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Serpens
Right ascension  15h 32m 09.67495s[1]
Declination +16° 03′ 22.2056″[1]
Apparent magnitude (V) 6.22[2]
Characteristics
Spectral type B9V[3]
U−B color index −0.23[4]
B−V color index −0.038±0.005[2]
Astrometry
Radial velocity (Rv)−19.3±2.7[2] km/s
Proper motion (μ) RA: −2.92[5] mas/yr
Dec.: +6.48[5] mas/yr
Parallax (π)6.7936 ± 0.0928[1] mas
Distance480 ± 7 ly
(147 ± 2 pc)
Absolute magnitude (MV)+0.44[2]
Details
Mass2.89±0.08[6] M☉
Radius2.7[7] R☉
Luminosity96.4+15.3
−12.6[6] L☉
Temperature10,839+60
−50[6] K
Rotational velocity (v sin i)154[6] km/s
Age278[8] Myr
Other designations
τ2 Ser, 12 Serpentis, BD+16°2797, GC 20880, HD 138527, HIP 76069, HR 5770, SAO 101600, PPM 131484[9]
Database references
SIMBADdata

This object is a late B-type main-sequence star with a stellar classification of B9V.[3] It is a probable Lambda Boötis star.[2][10] The star is 278[8] million years old and is spinning with a projected rotational velocity of 154 km/s.[6] It has nearly three times the mass and radius of the Sun.[6][7] Tau2 Serpentis is radiating 96[6] times the Sun's luminosity from its photosphere at an effective temperature of 10,839 K.[6]

There is evidence of a possible companion, which is contributing about 15% to the total emission of the system.[11]

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.
  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. Hoffleit, D.; Warren, Jr., W. H., The Bright Star Catalogue (5th Revised ed.), CDS. HR 5770. Accessed on line September 19, 2008.
  5. 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.
  6. 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.
  7. Pasinetti Fracassini, L. E.; et al. (2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy & Astrophysics (Third ed.), 367 (2): 521–24, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451. HD 138527 Accessed on line September 19, 2008.
  8. Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035.
  9. "tau02 Ser". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-18.
  10. Murphy, Simon J.; et al. (October 2015), "An Evaluation of the Membership Probability of 212 λ Boo Stars. I. A Catalogue", Publications of the Astronomical Society of Australia, 32: 43, arXiv:1508.03633, Bibcode:2015PASA...32...36M, doi:10.1017/pasa.2015.34, e036
  11. Zverko, J.; et al. (January 2013), "Stars with discrepant v sin i as derived from Ca II λ 3933 Å and Mg II λ 4481 Å lines. III. Stars with v sin i ( λ 3933 Å) < v sin i ( λ 4481 Å)", Astrophysical Bulletin, 68 (1): 57–77, Bibcode:2013AstBu..68...57Z, doi:10.1134/S1990341313010069.
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