Mu2 Gruis

Mu2 Gruis, Latinized from μ2 Gruis, is a yellow-hued star or star system in the southern constellation of Grus. It is a suspected astrometric binary, showing a variation in proper motion due to gravitational acceleration.[7] Mu2 Gruis is visible to the naked eye with an apparent visual magnitude of 5.10.[2] The distance to this system, as determined using an annual parallax shift of 13.2 mas as seen from the Earth,[1] is around 248 light years. It is drifting further away with a heliocentric radial velocity of +12.5 km/s.[4]

For other stars with this Bayer designation, see μ Gruis.
Mu2 Gruis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Grus
Right ascension  22h 16m 26.54790s[1]
Declination −41° 37′ 37.8266″[1]
Apparent magnitude (V) 5.10[2]
Characteristics
Spectral type G8 III[3]
B−V color index +0.92[2]
Astrometry
Radial velocity (Rv)+12.50[4] km/s
Proper motion (μ) RA: −14.788[1] mas/yr
Dec.: −15.530[1] mas/yr
Parallax (π)13.1578 ± 0.1559[1] mas
Distance248 ± 3 ly
(76.0 ± 0.9 pc)
Absolute magnitude (MV)+0.56[5]
Details
Radius9.97+0.32
−0.20[1] R☉
Luminosity56.37±0.78[1] L☉
Temperature5009+52
−79[1] K
Other designations
μ2 Gru, CD−42° 15846, HD 211202, HIP 109973, HR 8488, SAO 231063[6]
Database references
SIMBADdata

The primary component is an evolved giant star with a stellar classification of G8 III.[3] It is a periodic variable star, showing a change in brightness with an amplitude of 0.004 magnitude at the rate of 7.50983 times per day.[8] With the supply of hydrogen at its core exhausted, the star has cooled and expanded until now it has 10 times the radius of the Sun. It is radiating 56[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 5,009 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. 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, N. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 2, Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  4. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065.
  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. "mu.02 Gru -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-06-26.
  7. 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.
  8. Koen, Chris; Eyer, Laurent (2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society, 331: 45, arXiv:astro-ph/0112194, Bibcode:2002MNRAS.331...45K, doi:10.1046/j.1365-8711.2002.05150.x.
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