60 Sagittarii

60 Sagittarii is a suspected binary star[10] system in the southern constellation of Sagittarius. It has the Bayer designation A Sagittarii, while 60 Sagittarii is the Flamsteed designation. This naked eye object forms the northwest corner of the asterism called the Terebellum and, with an apparent magnitude of approximately 4.84,[2] it is the dimmest of the four stars in the Terebellum. It is located 379 light years from the Sun, based on parallax, but is moving closer with a radial velocity of −51 km/s.[2]

60 Sagittarii

The four stars of the Terebellum
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagittarius
Right ascension 19h 58m 57.20292s[1]
Declination −26° 11′ 44.7585″[1]
Apparent magnitude (V) 4.84[2]
Characteristics
Evolutionary stage horizontal branch[3]
Spectral type G6 III[4]
U−B color index +0.55[5]
B−V color index +0.882±0.038[2]
R−I color index +0.47[5]
Astrometry
Radial velocity (Rv)−51.1±2.4[2] km/s
Proper motion (μ) RA: +35.31[6] mas/yr
Dec.: +25.69[6] mas/yr
Parallax (π)8.6025 ± 0.1732[1] mas
Distance379 ± 8 ly
(116 ± 2 pc)
Absolute magnitude (MV)−0.07[2]
Details
Radius17.42+0.68
−0.80[1] R☉
Luminosity170.3±4.0[1] L☉
Surface gravity (log g)2.78[7] cgs
Temperature4,997+119
−96[1] K
Metallicity [Fe/H]−0.38[7] dex
Other designations
A Sgr[8], 60 Sgr, CD−26°14682, CPD−26°6895, GC 27658, HD 189005, HIP 98353, HR 7618, SAO 188778, PPM 270516[9]
Database references
SIMBADdata

The visible component is an aging G-type giant star with a stellar classification of G6 III,[4] having exhausted the supply of hydrogen at its core and expanded to 17[1] the Sun's radius. In the Bright Star Catalogue it was listed with a class of G6 III Ba0.2,[5] suggesting it is a mild barium star and thus might have a white dwarf companion.[10] It is a red clump giant, indicating it is on the horizontal branch and is generating energy through the fusion of helium at its core.[3] The star is radiating 170[1] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,997 K.[1]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 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.
  3. Alves, David R. (August 2000), "K-Band Calibration of the Red Clump Luminosity", The Astrophysical Journal, 539 (2): 732–741, arXiv:astro-ph/0003329, Bibcode:2000ApJ...539..732A, doi:10.1086/309278, S2CID 16673121.
  4. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  5. Hoffleit, D.; Warren, Jr., W. H., "HR 7618, database record", The Bright Star Catalogue (5th Revised ed.), CDS. ID V/50. Accessed on line November 19, 2009.
  6. 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, S2CID 18759600.
  7. Alves, S.; et al. (April 2015), "Determination of the spectroscopic stellar parameters for 257 field giant stars", Monthly Notices of the Royal Astronomical Society, 448 (3): 2749–2765, arXiv:1503.02556, Bibcode:2015MNRAS.448.2749A, doi:10.1093/mnras/stv189, S2CID 119217930.
  8. Kostjuk, N. D. (2002), "HD 189005, database record", HD-DM-GC-HR-HIP-Bayer-Flamsteed Cross Index, Institute of Astronomy of Russian Academy of Sciences. CDS ID IV/27. Accessed on line November 19, 2009.
  9. "60 Sgr A". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-08-04.
  10. Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
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