68 Aquarii

68 Aquarii is a single[6] star located 270 light years away from the Sun in the zodiac constellation of Aquarius. 68 Aquarii is its Flamsteed designation, though it also bears the Bayer designation of g2 Aquarii.[7] It is visible to the naked eye as a dim, yellow-hued star with an apparent visual magnitude of 5.24.[2] The object is moving further from the Earth with a heliocentric radial velocity of +24.5 km/s.[2]

This article is about g2 Aquarii. For other stars with this Bayer designation, see g Aquarii.
68 Aquarii
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Aquarius
Right ascension  22h 47m 33.12362s[1]
Declination −19° 36′ 48.1619″[1]
Apparent magnitude (V) 5.24[2]
Characteristics
Spectral type G8III
B−V color index +0.941±0.002[2]
Astrometry
Radial velocity (Rv)+24.54±0.27[2] km/s
Proper motion (μ) RA: −103.390[1] mas/yr
Dec.: −205.545[1] mas/yr
Parallax (π)12.0902 ± 0.1605[1] mas
Distance270 ± 4 ly
(83 ± 1 pc)
Absolute magnitude (MV)0.78[2]
Details
Mass1.39[3] M☉
Radius10.05+0.35
−1.62[1] R☉
Luminosity58.5±0.9[1] L☉
Surface gravity (log g)2.8[4] cgs
Temperature5,036+461
−85[1] K
Metallicity [Fe/H]−0.43±0.02[2] dex
Rotational velocity (v sin i)0.0[4] km/s
Age3.79[3] Gyr
Other designations
68 Aqr, BD−20°6486, HD 215721, HIP 112529, HR 8670, SAO 165293, LTT 9194[5]
Database references
SIMBADdata

This star is 3.79[3] billion years old with a stellar classification of G8 III,[8] indicating the is a giant star that has exhausted the hydrogen at its core and expanded off the main sequence. It is a red clump giant,[9] which means it is on the horizontal branch and is generating energy through helium fusion at its core. It has 1.39[3] times the mass of the Sun and 10 times the Sun's radius. The star is radiating 59 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 5,036 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.
  3. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88.
  4. Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209.
  5. "68 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-05-18.
  6. 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.
  7. Kostjuk, N. D. (2002), "HD 215721", HD-DM-GC-HR-HIP-Bayer-Flamsteed Cross Index, Institute of Astronomy of Russian Academy of Sciences, retrieved 2019-05-19; CDS ID IV/27A.
  8. Houk, Nancy (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.
  9. 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
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