Xi2 Sagittarii

Xi2 Sagittarii (ξ2 Sagittarii) is a star in the zodiac constellation of Sagittarius. Data collected during the Hipparcos mission suggests it is an astrometric binary, although nothing is known about the companion.[9][10] It is visible to the naked eye with a combined apparent visual magnitude of +3.51.[2] Based upon an annual parallax shift of 8.93 mas as seen from Earth,[1] this system is located around 370 light years from the Sun.

For other stars with this Bayer designation, see ξ Sagittarii.
Xi2 Sagittarii
Location of ξ2 Sagittarii (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagittarius
Right ascension  18h 57m 43.79908s[1]
Declination −21° 06′ 23.9613″[1]
Apparent magnitude (V) +3.51[2]
Characteristics
Spectral type G8/K0 II/III[3]
U−B color index +1.13[2]
B−V color index +1.18[2]
Astrometry
Radial velocity (Rv)−20.10[4] km/s
Proper motion (μ) RA: +31.72[1] mas/yr
Dec.: −13.33[1] mas/yr
Parallax (π)8.93 ± 0.53[1] mas
Distance370 ± 20 ly
(112 ± 7 pc)
Absolute magnitude (MV)−1.72[5]
Details
Mass3.36[4] M☉
Radius14[6] R☉
Luminosity676[4] L☉
Surface gravity (log g)2.23[7] cgs
Temperature4,541±64[4] K
Metallicity [Fe/H]−0.19[7] dex
Age380[4] Myr
Other designations
ξ2 Sgr, 37 Sgr, BD−21° 5201, FK5 710, HD 175775, HIP 93085, HR 7150, SAO 187504[8]
Database references
SIMBADdata

The spectrum of Xi2 Sagittarii yields a mixed stellar classification of G8/K0 II/III,[3] showing traits of a G- or K-type giant or bright giant star. It has an estimated 3.36[4] times the mass of the Sun and about 14 times the Sun's radius.[6] At an age of around 380 million years, it is radiating 676 times the Sun's luminosity from its photosphere at an effective temperature of 4,541 K.[4]

References
  1. 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.
  2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J.
  3. Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
  4. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88.
  5. 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.
  6. Pasinetti Fracassini, L. E.; et al. (2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy & Astrophysics (3rd ed.), 367: 521–24, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  7. McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series, 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527.
  8. "ksi02 Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-05.
  9. Frankowski, A.; et al. (March 2007), "Proper-motion binaries in the Hipparcos catalogue. Comparison with radial velocity data", Astronomy and Astrophysics, 464 (1): 377–392, arXiv:astro-ph/0612449, Bibcode:2007A&A...464..377F, doi:10.1051/0004-6361:20065526.
  10. Makarov, V. V.; Kaplan, G. H. (May 2005), "Statistical Constraints for Astrometric Binaries with Nonlinear Motion", The Astronomical Journal, 129 (5): 2420–2427, Bibcode:2005AJ....129.2420M, doi:10.1086/429590.
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