Astronomy:Zeta Arae

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Short description: Star in the constellation Ara
ζ Arae
Location of ζ Arae (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Ara
Right ascension  16h 58m 37.213s[1]
Declination −55° 59′ 24.50″[1]
Apparent magnitude (V) 3.13[2]
Characteristics
Evolutionary stage AGB[3]
Spectral type K3 III[4]
U−B color index +1.96[2]
B−V color index +1.60[2]
Astrometry
Radial velocity (Rv)−6.0±0.6[5] km/s
Proper motion (μ) RA: −17.518[1] mas/yr
Dec.: −36.120[1] mas/yr
Parallax (π)5.7725 ± 0.1727[1] mas
Distance570 ± 20 ly
(173 ± 5 pc)
Absolute magnitude (MV)−3.95[6]
Details
Mass7–8[7] M☉
Radius114±4[7] R☉
Luminosity3,800+464−414[7] L☉
Surface gravity (log g)1.200±0.004[7] cgs
Temperature4,246+99−96[7] K
Metallicity [Fe/H]−0.40[8] dex
Other designations
Tseen Yin, ζ Arae, CPD−55°7766, FK5 631, GC 22845, GJ 9581, HD 152786, HIP 83081, HR 6285, SAO 244315, PPM 345563[9]
Database references
SIMBADdata
ARICNSdata

Zeta Arae is the third-brightest star in the southern constellation Ara.[10] 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.[5]

The spectrum of this star matches a stellar classification of K3 III.[4] 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.[6][11] 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[7] times the luminosity of the Sun from its photosphere at an effective temperature of 4,246 K,[7] giving it the orange hue of a K-type star.[12]

In 1997, an excess of infrared emission was announced that may indicate circumstellar matter.[13] However, a 2015 study found no excess.[14] 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.[15]

Nomenclature

In Chinese, 龜 (Guī), meaning Tortoise, refers to an asterism consisting of ζ Arae, ε1 Arae, γ Arae, δ Arae and η Arae.[16] Consequently, the Chinese name for ζ Arae itself is 龜五 (Guī wǔ, English: the Fifth Star of Tortoise.)[17]

R. H. Allen called it Tseen Yin /ˌsiːnˈjɪn/, together with δ Arae, from the Chinese 天陰 (Mandarin pronunciation tiānyīn) "dark sky".[18] However, 天陰 is in Aries.[19][20] so Allen probably confused constellation "Ara" with "Ari".

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 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. ↑ McDonald, I.; Srinivasan, S.; Scicluna, P.; Jones, O. C.; Zijlstra, A. A.; Wallström, S. H. J.; Danilovich, T.; He, J. H. et al. (2025). "The Nearby Evolved Stars Survey (NESS) V: Properties of volume-limited samples of Galactic evolved stars". Monthly Notices of the Royal Astronomical Society 541 (1): 516. doi:10.1093/mnras/staf978. Bibcode: 2025MNRAS.541..516M. 
  4. ↑ 4.0 4.1 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 (Ann Arbor: Dept. of Astronomy, University of Michigan) 1, Bibcode: 1975mcts.book.....H. 
  5. ↑ 5.0 5.1 Gontcharov, G. A. (2006), "Pulkovo compilation of radial velocities for 35495 stars in a common system", Astronomy Letters 32 (11): 759–771, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G. 
  6. ↑ 6.0 6.1 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. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 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, doi:10.1093/mnras/stt1037, Bibcode: 2013MNRAS.434..437C. 
  8. ↑ 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, doi:10.1093/mnras/256.3.535, Bibcode: 1992MNRAS.256..535J. 
  9. ↑ "zet Ara". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=zet+Ara. 
  10. ↑ Kaler, Jim (July 13, 2012), Zeta Arae, University of Illinois, http://stars.astro.illinois.edu/sow/zetaara.html, retrieved 12 September 2019. 
  11. ↑ Kratka, T.; Stefl, V. (2007), "HD152786: a Lithium Giant?", Odessa Astronomical Publications 20: 95, Bibcode: 2007OAP....20...95K. 
  12. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved 2012-01-16. 
  13. ↑ Plets, H. et al. (July 1997), "Giants with infrared excess", Astronomy and Astrophysics 323: 513–523, Bibcode: 1997A&A...323..513P. 
  14. ↑ Rebull, Luisa M. et al. (October 2015), "On Infrared Excesses Associated with Li-rich K Giants", The Astronomical Journal 150 (4): 45, doi:10.1088/0004-6256/150/4/123, 123, Bibcode: 2015AJ....150..123R. 
  15. ↑ 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, doi:10.1051/0004-6361/202142146, ISSN 0004-6361, Bibcode: 2022A&A...657A...7K. 
  16. ↑ (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.
  17. ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 1 日
  18. ↑ 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, https://archive.org/details/bub_gb_5xQuAAAAIAAJ. 
  19. ↑ 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.
  20. ↑ 伊世同 (Yi Shi Tong) (1981): 『中西対照恒星図表』科学出版社.(in Chinese)



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