Beta Gruis

Beta Gruis
Location of β Gruis (circled)
Observation data
Epoch J2000      Equinox ICRS
Constellation Grus
Right ascension 22h 42m 40.05027s
Declination −46° 53′ 04.4752″
Apparent magnitude (V) 2.0 - 2.3
Characteristics
Evolutionary stage AGB
Spectral type M4.5 III
U−B color index +1.757
B−V color index +1.620
Variable type SRb
Astrometry
Radial velocity (Rv)+1.6 km/s
Proper motion (μ) RA: +135.16 mas/yr
Dec.: −4.38 mas/yr
Parallax (π)18.43±0.42 mas
Distance177 ± 4 ly
(54 ± 1 pc)
Absolute magnitude (MV)−1.61±0.052
Details
Mass2.4 M☉
Radius154 R☉
Luminosity3,221±242 L☉
Surface gravity (log g)0.4 cgs
Temperature3,508±125 K
Metallicity [Fe/H]0.0 dex
Age450 Myr
Other designations
Tiaki, Beta Gru, CD−47 14308, FK5 856, HR 8636, HD 214952, HIP 112122, SAO 231258.
Database references
SIMBADdata

Beta Gruis (β Gruis, abbreviated Beta Gru, β Gru), formally named Tiaki /tiˈɑːki/, is the second brightest star in the southern constellation of Grus. It was once considered the rear star in the tail of the constellation of the (Southern) Fish, Piscis Austrinus: it, with Alpha, Delta, Theta, Iota, and Lambda Gruis, belonged to Piscis Austrinus in medieval Arabic astronomy.

Nomenclature

β Gruis (Latinised to Beta Gruis) is the star's Bayer designation.

It bore the traditional Tuamotuan name of Tiaki. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name Tiaki for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.

In Chinese, 鶴 (Hè), meaning Crane, refers to an asterism consisting of Beta Gruis, Alpha Gruis, Epsilon Gruis, Eta Gruis, Delta Tucanae, Zeta Gruis, Iota Gruis, Theta Gruis, Delta² Gruis and Mu¹ Gruis. Consequently, Beta Gruis itself is known as 鶴二 (Hè èr, English: Second Star of the Crane). The Chinese name gave rise to another English name, Ke.

Properties

A visual band light curve for Beta Gruis, plotted from data published by Otero and Moon (2006). The inset plot shows the points plotted in red with an expanded scale.

Beta Gruis is a red giant star on the asymptotic giant branch with an estimated mass of about 2.4 times that of the Sun and a surface temperature of approximately 3,500 K, just over half the surface temperature of the Sun. This low temperature accounts for the dull red color of an M-type star. The total luminosity is about 3,200 times that of the Sun, and it has 150 times the Sun's radius.

It is one of the brightest stars at infrared and near-infrared wavelengths. At the K band, it is the fifth-brightest star in the night sky.

Alan William James Cousins announced that Beta Gruis is a variable star in 1952. Beta Gruis is a semiregular variable (SRb) star that varies in magnitude by about 0.4. It varies between intervals when it displays regular changes with a 37-day periodicity and times when it undergoes slow irregular variability.

References

  1. 1 2 3 4 5 van Leeuwen, F. (November 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
  2. 1 2 3 4 5 Otero, S. A.; Moon, T. (December 2006), "The Characteristic Period of Pulsation of β Gruis", The Journal of the American Association of Variable Star Observers, 34 (2): 156–164, Bibcode:2006JAVSO..34..156O
  3. 1 2 Eggen, Olin J. (July 1992). "Asymptotic giant branch stars near the sun". Astronomical Journal. 104 (1): 275–313. Bibcode:1992AJ....104..275E. doi:10.1086/116239.
  4. ↑ Răstău, V.; Mečina, M.; Kerschbaum, F.; Olofsson, H.; Maercker, M.; Drechsler, M.; Strottner, X.; Mulato, L. (2023-12-01). "Extended far-UV emission surrounding asymptotic giant branch stars as seen by GALEX". Astronomy & Astrophysics. 680: A12. arXiv:2310.09056. Bibcode:2023A&A...680A..12R. doi:10.1051/0004-6361/202346120. ISSN 0004-6361.
  5. 1 2 Gutierrez-Moreno, Adelina; et al. (1966), "A System of photometric standards", Publ. Dept. Astron. Univ. Chile, 1, Publicaciones Universidad de Chile, Department de Astronomy: 1–17, Bibcode:1966PDAUC...1....1G
  6. ↑ Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veröff. Astron. Rechen-Inst. Heidelb, 35 (35), Astronomisches Rechen-Institut Heidelberg: 1, Bibcode:1999VeARI..35....1W
  7. ↑ Park, Sunkyung; et al. (2013), "Wilson-Bappu Effect: Extended to Surface Gravity", The Astronomical Journal, 146 (4): 73, arXiv:1307.0592, Bibcode:2013AJ....146...73P, doi:10.1088/0004-6256/146/4/73, S2CID 119187733.
  8. ↑ Gondoin, P. (December 1999), "Evolution of X-ray activity and rotation on G-K giants", Astronomy and Astrophysics, 352: 217–227, Bibcode:1999A&A...352..217G
  9. 1 2 3 4 5 McDonald, I.; Zijlstra, A. A.; Watson, R. A. (2017-10-01). "Fundamental parameters and infrared excesses of Tycho-Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770–791. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433. ISSN 0035-8711.
  10. 1 2 Judge, P. G. (November 1986), "Constraints on the Outer Atmospheric Structure of Late Type Giant Stars with IUE Application to Alpha-Tauri K5III and Beta-Gruis M5III", Monthly Notices of the Royal Astronomical Society, 223 (2): 239, Bibcode:1986MNRAS.223..239J, doi:10.1093/mnras/223.2.239
  11. ↑ Kaler, Jim. "Beta Gruis". stars.astro.illinois.edu. Retrieved 2024-09-21.
  12. ↑ "V* bet Gru -- Variable Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2010-01-05
  13. 1 2 "Naming Stars". IAU.org. Archived from the original on 10 March 2025. Retrieved 16 December 2017.
  14. 1 2 Allen, Richard Hinckley (1936) [1899]. Star Names and Their Meanings. New York: G. E. Stechert. p. 238. OCLC 9825499.
  15. ↑ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 7. Archived from the original (PDF) on 2019-08-23. Retrieved 2018-07-14.
  16. ↑ "IAU Working Group on Star Names (WGSN)". Archived from the original on 10 June 2016. Retrieved 22 May 2016.
  17. ↑ (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.
  18. ↑ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2008-10-25 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  19. ↑ Engelke, Charles W.; Price, Stephan D.; Kraemer, Kathleen E. (October 2006), "Spectral Irradiance Calibration in the Infrared. XVI. Improved Accuracy in the Infrared Spectra of the Secondary and Tertiary Standard Calibration Stars", The Astronomical Journal, 132 (4): 1445–1463, Bibcode:2006AJ....132.1445E, doi:10.1086/505865
  20. ↑ "Kmag < -3.22". SIMBAD. Retrieved July 1, 2024.
  21. ↑ Cousins, A. W. J. (April 1952). "Bright variable stars in southern hemisphere (second list)". The Observatory. 72: 86–87. Bibcode:1952Obs....72...86C.