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Eta Gruis, Latinized from η Gruis, is a solitary star in the southern constellation of Grus. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.85. Based upon an annual parallax shift of 7.1 mas as seen from the Earth, the system is located about 460 light years from the Sun. The star is drifting further away with a radial velocity of +28 km/s.

This object is an evolved K-type giant star with a stellar classification of K2 III CNIV, where the suffix notation indicates this is an intermediate CN star. It is a periodic microvariable with an amplitude of 0.0055 magnitude and a frequency of 0.36118 cycles per day. With the supply of hydrogen exhausted at its core, the star has expanded and cooled, now having 31 times the Sun's girth. It is radiating 338.5 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,420 K.

Eta Gruis has a magnitude 11.5 visual companion located at an angular separation of 25.6″ along a position angle of 187°, as of 2012.

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): 99, Bibcode:1966CoLPL...4...99J.
3. ^ Houk, Nancy; Cowley, A. P. (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 1, Ann Arbor, Michigan: 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, S2CID 119231169.
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. "eta Gru". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-28.
7. 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, S2CID 14878976.
8. 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.
9. Koen, Chris; Eyer, Laurent (2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society, 331 (1): 45–59, arXiv:astro-ph/0112194, Bibcode:2002MNRAS.331...45K, doi:10.1046/j.1365-8711.2002.05150.x, S2CID 10505995.
10. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.

v t e Constellation of Grus
List of stars in Grus List of star names in Grus Grus in Chinese astronomy
Stars	Bayer α (Alnair) β (Tiaki) γ (Aldhanab) δ δ ε ζ η θ ι κ λ μ μ ν ξ ο π π ρ σ σ τ τ τ υ φ Variable RZ CE HR 8323 8501 HD 208487 (Itonda) 213240 215456 Other 2MASS J22282889–4310262 Gliese 832 PSR J2144−3933 S5-HVS1 WASP-95 WISE 2220−3628
Exoplanets Gliese 832 b HD 208487 b HD 213240 b τ Gruis b
Galaxies	NGC 7070 7070A 7072 7075 7079 7087 7213 7418 7424 7496 7531 7552 7582 7590 Other IC 1459 IC 5201
Galaxy clusters Abell S1063
Category

• K-type giants
• Grus (constellation)
• Bayer objects
• Durchmusterung objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Bright Star Catalogue objects