Xi2 Sagittarii

Xi² Sagittarii, Latinized from 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.^[8][9] It is visible to the naked eye with a combined apparent visual magnitude of +3.51.^[2] Based upon an annual parallax shift of 8.4 mas as seen from Earth,^[1] this system is located around 390 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 43.80s[1]
Declination	−21° 06′ 23.97″[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: 33.52 mas/yr[1] Dec.: -13.552 mas/yr[1]
Parallax (π)	8.4092 ± 0.1972 mas[1]
Distance	388 ± 9 ly (119 ± 3 pc)[1]
Absolute magnitude (MV)	−1.72[5]
Details[6]
Mass	3.627±0.143 M☉
Radius	26.747±1.97 R☉
Luminosity	676[4] L☉
Surface gravity (log g)	2.39±0.19 cgs
Temperature	4,682±75 K
Metallicity [Fe/H]	0±0.5 dex
Age	253±33 Myr
Other designations
ξ2 Sgr, 37 Sgr, BD−21° 5201, FK5 710, HD 175775, HIP 93085, HR 7150, SAO 187504[7]
Database references
SIMBAD	data

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 3.6 times the mass of the Sun and about 27 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. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
3. Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 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, S2CID 118505114.
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, S2CID 119257644.
6. Gomes da Silva, J.; Santos, N. C.; Adibekyan, V.; Sousa, S. G.; Campante, T. L.; Figueira, P.; Bossini, D.; Delgado-Mena, E.; Monteiro, M. J. P. F. G.; de Laverny, P.; Recio-Blanco, A.; Lovis, C. (2021-02-01). "Stellar chromospheric activity of 1674 FGK stars from the AMBRE-HARPS sample. I. A catalogue of homogeneous chromospheric activity". Astronomy and Astrophysics. 646: A77. arXiv:2012.10199. Bibcode:2021A&A...646A..77G. doi:10.1051/0004-6361/202039765. ISSN 0004-6361. Xi2 Sagittarii's database entry at VizieR.
7. "ksi02 Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-05.
8. 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, S2CID 14010423.
9. 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.