Eta Circini

Eta Circini, Latinized from η Circini, is the Bayer designation for a solitary[9] star located in the southern constellation of Circinus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.17.[2] The distance to this star, as determined from an annual parallax shift of 11.82 mas,[1] is around 276 light years.

η Circini
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Circinus
Right ascension  15h 04m 48.18600s[1]
Declination −64° 01′ 52.8611″[1]
Apparent magnitude (V) 5.17[2]
Characteristics
Spectral type G8 III[3]
B−V color index +0.93[2]
Astrometry
Radial velocity (Rv)44.8±0.8[4] km/s
Proper motion (μ) RA: +102.65[1] mas/yr
Dec.: +9.35[1] mas/yr
Parallax (π)11.82 ± 0.30[1] mas
Distance276 ± 7 ly
(85 ± 2 pc)
Absolute magnitude (MV)+0.52[5]
Details
Luminosity64[6] L☉
Surface gravity (log g)2.69±0.05[7] cgs
Temperature4,954±22[7] K
Metallicity [Fe/H]−0.37±0.02[7] dex
Other designations
η Cir, CPD−63° 3493, HD 132905, HIP 73776, HR 5593, SAO 253005.[8]
Database references
SIMBADdata

This is an evolved G-type giant star with a stellar classification of G8 III.[3] It is radiating an estimated 64[6] times the solar luminosity from its outer atmosphere at an effective temperature of 4,954 K.[7]

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. Corben, P. M.; Stoy, R. H. (1968), "Photoelectric Magnitudes and Colours for Bright Southern Stars", Monthly Notes of the Astronomical Society of Southern Africa, 27: 11, Bibcode:1968MNSSA..27...11C.
  3. Houk, Nancy; Cowley, A. P. (1979), University of Michigan Catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Department of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  4. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35,495 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. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  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.
  8. "eta Cir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-01-18.
  9. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
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