Zeta2 Scorpii

Zeta2 Scorpii (Zeta2 Sco, ζ2 Scorpii, ζ2 Sco) is a K-type orange giant star in the constellation of Scorpius.[8] 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 Earth's 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 132 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 astrophotographs.

For other stars with this Bayer designation, see Zeta Scorpii.
ζ2 Scorpii
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Scorpius
Right ascension 16h 54m 35.00435s[1]
Declination −42° 21′ 40.7407″[1]
Apparent magnitude (V) 3.59 to 3.65[2]
Characteristics
Spectral type K4 III[3]
U−B color index +1.65[4]
B−V color index +1.37[4]
R−I color index +0.68[4]
Astrometry
Radial velocity (Rv)−18.7±0.9[5] km/s
Proper motion (μ) RA: −127.72[1] mas/yr
Dec.: −229.44[1] mas/yr
Parallax (π)24.65 ± 0.27 mas[1]
Distance132 ± 1 ly
(40.6 ± 0.4 pc)
Absolute magnitude (MV)0.30±0.09[6]
Details
Mass1.19±0.14[6] M☉
Radius21.0±1.6[6] R☉
Surface gravity (log g)1.84±0.10[6] cgs
Temperature4,169[6] K
Metallicity [Fe/H]+0.06[6] dex
Rotational velocity (v sin i)2.30[7] km/s
Age5.80±2.26[6] 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.[8]
Database references
SIMBADdata
Reddish ζ2 Scorpii alongside the fainter ζ1 Scorpii to the south of NGC 6231

References
  1. van Leeuwen, F. (November 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, S2CID 18759600.
  2. 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. Landi Dessy, J.; Keenan, P. C. (November 1966), "Spectral Types on the MK System for Forty-Three Bright Southern Stars, K2-M6", Astrophysical Journal, 146: 587, Bibcode:1966ApJ...146..587L, doi:10.1086/148925.
  4. 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.
  5. Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick (eds.), "The Revision of the General Catalogue of Radial Velocities", Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, vol. 30, p. 57, Bibcode:1967IAUS...30...57E.
  6. 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, S2CID 9341088.
  7. Jofré, E.; Petrucci, R.; Saffe, C.; Saker, L.; de la Villarmois, E. Artur; Chavero, C.; Gómez, M.; Mauas, P. J. D. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574: A50, arXiv:1410.6422, Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474, S2CID 53666931, A50.
  8. "zet02 Sco". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-09-20.
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