Tau2 Serpentis

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τ2 Serpentis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Serpens
Right ascension 15h 32m 09.6751s[1]
Declination +16° 03′ 22.208″[1]
Apparent magnitude (V) 6.218[1]
Spectral type B9V[1]
U−B color index −0.23[2]
B−V color index −0.05[2]
Radial velocity (Rv)−18 ± 5[1] km/s
Proper motion (μ) RA: −2.87[1] mas/yr
Dec.: 6.76[1] mas/yr
Parallax (π)7.56 ± 0.80[1] mas
Distanceapprox. 430 ly
(approx. 130 pc)
Absolute magnitude (MV)+0.44[3]
Radius2.7[4] R
Luminosity74[3] L
Rotational velocity (v sin i)175[2] km/s
Other designations
τ2 Ser, 12 Serpentis, BD+16° 2797, GC 20880, HD 138527, HIP 76069, HR 5770, SAO 101600, PPM 131484[1]
Database references

Tau2 Serpentis, Latinized from τ2 Serpentis, is a B-type main sequence star in the constellation of Serpens, approximately 430 light-years from Earth. It has an apparent visual magnitude of approximately 6.218.[1] This is a Lambda Boötis star.[3]


  1. ^ a b c d e f g h i j * 12 Ser -- Star, database entry, SIMBAD. Accessed on line September 19, 2008.
  2. ^ a b c HR 5770, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 19, 2008.
  3. ^ a b c Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971Freely accessible, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. 
  4. ^ HD 138527, database entry, Catalog of Apparent Diameters and Absolute Radii of Stars (CADARS), 3rd edition, L. E. Pasinetti-Fracassini, L. Pastori, S. Covino, and A. Pozzi, CDS ID II/224. Accessed on line September 19, 2008.