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Zeta Arae

Zeta Arae is the third-brightest star in the southern constellation Ara.[9] Its name is a Bayer designation that is Latinized from ζ Arae, and abbreviated Zeta Ara or ζ Ara. The apparent visual magnitude of this star is 3.1,[2] which can be seen with the naked eye from suburban skies in the southern hemisphere. From the parallax measurements, it is located at a distance of approximately 490 light-years (150 parsecs) from Earth.[1] The star is drifting closer to the Sun with a radial velocity of 6 km/s.[4]

The spectrum of this star matches a stellar classification of K3 III.[3] The luminosity class of 'III' indicates this is a giant star that has exhausted the hydrogen at its core and evolved away from the main sequence. However, some studies have suggested it is instead a supergiant.[5][10] The star has 7-8 times the mass of the Sun and has expanded to 114 times the Sun's girth. It is radiating 3,800[6] times the luminosity of the Sun from its photosphere at an effective temperature of 4,246 K,[6] giving it the orange hue of a K-type star.[11]

In 1997, an excess of infrared emission was announced that may indicate circumstellar matter.[12] However, a 2015 study found no excess.[13] A candidate gravitationally bound companion was announced in 2022. This object lies at an angular separation of 138.4″ from Zeta Arae, which is equivalent to a projected separation of 20.63×103 au.[14]

Nomenclature

In Chinese, 龜 (Guī), meaning Tortoise, refers to an asterism consisting of ζ Arae, ε1 Arae, γ Arae, δ Arae and η Arae.[15] Consequently, the Chinese name for ζ Arae itself is 龜五 (Guī wǔ, English: the Fifth Star of Tortoise.)[16]

R. H. Allen called it Tseen Yin /ˌsiːnˈjɪn/, together with δ Arae, from the Chinese 天陰 (Mandarin pronunciation tiānyīn) "dark sky".[17] However, 天陰 is in Aries.[18][19] so Allen probably confused constellation "Ara" with "Ari".

References

  1. ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. ^ a b c d 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. ^ a b Houk, Nancy (1978), "Michigan catalogue of two-dimensional spectral types for the HD stars", University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations -90_ to -53_ƒ0, 1, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1975mcts.book.....H.
  4. ^ a b Gontcharov, G. A. (2006), "Pulkovo compilation of radial velocities for 35495 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. ^ a b Jasniewicz, G.; et al. (February 1999), "Late-type giants with infrared excess. I. Lithium abundances", Astronomy and Astrophysics, 342: 831–838, Bibcode:1999A&A...342..831J.
  6. ^ a b c d e f g Cruzalèbes, P.; et al. (2013), "Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI/AMBER", Monthly Notices of the Royal Astronomical Society, 434 (1): 437, arXiv:1306.3288, Bibcode:2013MNRAS.434..437C, doi:10.1093/mnras/stt1037, S2CID 49573767.
  7. ^ Jones, K. L.; et al. (June 1992), "Spectroscopic investigation of cool giants and the authenticity of their reported microwave emission", Monthly Notices of the Royal Astronomical Society, 256 (3): 535–544, Bibcode:1992MNRAS.256..535J, doi:10.1093/mnras/256.3.535.
  8. ^ "zet Ara", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2012-01-05.
  9. ^ Kaler, Jim (July 13, 2012), "Zeta Arae", Stars, University of Illinois, retrieved 12 September 2019.
  10. ^ Kratka, T.; Stefl, V. (2007), "HD152786: a Lithium Giant?", Odessa Astronomical Publications, 20: 95, Bibcode:2007OAP....20...95K.
  11. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2013-12-03, retrieved 2012-01-16.
  12. ^ Plets, H.; et al. (July 1997), "Giants with infrared excess", Astronomy and Astrophysics, 323: 513–523, Bibcode:1997A&A...323..513P.
  13. ^ Rebull, Luisa M.; et al. (October 2015), "On Infrared Excesses Associated with Li-rich K Giants", The Astronomical Journal, 150 (4): 45, arXiv:1507.00708, Bibcode:2015AJ....150..123R, doi:10.1088/0004-6256/150/4/123, S2CID 46595131, 123.
  14. ^ Kervella, Pierre; et al. (January 2022), "Stellar and substellar companions from Gaia EDR3. Proper-motion anomaly and resolved common proper-motion pairs", Astronomy and Astrophysics, 657: A7, arXiv:2109.10912, Bibcode:2022A&A...657A...7K, doi:10.1051/0004-6361/202142146, ISSN 0004-6361.
  15. ^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  16. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 1 日 Archived 2011-09-28 at the Wayback Machine
  17. ^ Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York, NY: Dover Publications Inc., p. 64, ISBN 0-486-21079-0. {{citation}}: ISBN / Date incompatibility (help)
  18. ^ Chevalier, S., and Tsuchihashi, P., (1911): "Catalogue d'Étoiles fixes, observés a Pekin sous l'Empereur Kien Long (Qianlong (Chien-Lung)), XVIIIe siecle", Annales de l'Observatoire Astronomique de Zô-Sé.
  19. ^ 伊世同 (Yi Shi Tong) (1981): 『中西対照恒星図表』科学出版社.(in Chinese)