Zeta2 Scorpii

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ζ2 Scorpii
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Scorpius
Right ascension 16h 54m 35.0053s[1]
Declination −42° 21′ 40.726″[1]
Apparent magnitude (V) 3.59 to 3.65[2]
Spectral type K4III[1]
U−B color index +1.65[3]
B−V color index +1.37[3]
R−I color index +0.68[3]
Radial velocity (Rv) −18.7 ± 0.9[1] km/s
Proper motion (μ) RA: −126.55[1] mas/yr
Dec.: −227.77[1] mas/yr
Parallax (π) 21.67 ± 0.85[1] mas
Distance 151 ± 6 ly
(46 ± 2 pc)
Absolute magnitude (MV) 0.30 ± 0.09[4]
Mass 1.19 ± 0.14[4] M
Radius 21.0 ± 1.6[4] R
Surface gravity (log g) 1.84 ± 0.10[4] cgs
Temperature 4,169[4] K
Metallicity [Fe/H] +0.06[4] dex
Age 5.80 ± 2.26[4] Gyr
Other designations
ζ2 Sco, Zeta2 Scorpii, Zeta2 Sco, CD−42 11646, CPD−42 7549, GC 22751, HD 152334, HIP 82729, HR 6271, LTT 6737, NLTT 43744, PPM 322371, SAO 227402.[1]
Database references
For other stars with this Bayer designation, see Zeta Scorpii.

Zeta2 Scorpii (Zeta2 Sco, ζ2 Scorpii, ζ2 Sco) is a K-type orange giant star in the constellation of Scorpius.[1] It has an apparent visual magnitude which varies between 3.59 and 3.65,[2] and is located near the blue-white supergiant star ζ1 Scorpii in our sky. In astronomical terms, ζ2 is much closer to the Sun and unrelated to ζ1 except for line-of sight co-incidence. ζ1 is 5,700 light-years away and probably an outlying member of open star cluster NGC 6231 (also known as the "northern jewel box" cluster), whereas ζ2 is a mere 151 lightyears distant and thus much less luminous in real terms. ζ2 can also be distinguished from its optical partner, ζ1, because of its orangish colour especially in long-exposure astrophographs.


  1. ^ a b c d e f g h i NSV 8028 -- Variable Star, database entry, SIMBAD. Accessed on line November 20, 2009.
  2. ^ a b NSV 8028, database entry, New Catalogue of Suspected Variable Stars, the improved version, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line November 20, 2009.
  3. ^ a b c HR 6271, 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 November 20, 2009.
  4. ^ a b c d e f g da Silva, L.; et al. (November 2006), "Basic physical parameters of a selected sample of evolved stars", Astronomy and Astrophysics 458 (2): 609–623, arXiv:astro-ph/0608160, Bibcode:2006A&A...458..609D, doi:10.1051/0004-6361:20065105