Astronomy:Gamma Gruis

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Short description: Star in the constellation Grus
Gamma Gruis
Grus IAU.svg
Red circle.svg
Location of γ Gruis (circled) near the center
Observation data
Equinox J2000.0]] (ICRS)
Constellation Grus
Right ascension  21h 53m 55.72620s[1]
Declination –37° 21′ 53.4790″[1]
Apparent magnitude (V) 3.003[2]
Characteristics
Spectral type B8 III[3] or B8IV-Vs[4]
U−B color index –0.307[2]
B−V color index –0.121[2]
Astrometry
Radial velocity (Rv)–2.1[5] km/s
Proper motion (μ) RA: +98.07[1] mas/yr
Dec.: –13.22[1] mas/yr
Parallax (π)15.45 ± 0.67[1] mas
Distance211 ± 9 ly
(65 ± 3 pc)
Absolute magnitude (MV)−1.05[6]
Details
Mass3.06[7] M☉
Radius4.5[8] R☉
Luminosity373[6] L☉
Surface gravity (log g)3.79[7] cgs
Temperature12,520[9] K
Rotation4.987[10] d
Rotational velocity (v sin i)57[11] km/s
Age75[7] Myr
Other designations
γ Gru, Gamma Gru, CD−37° 9119, FK5 822, GC 30640, HD 207971, HIP 108085, HR 8353, SAO 213374[12]
Database references
SIMBADdata

Gamma Gruis or γ Gruis, formally named Aldhanab (/ˈældənæb/),[13] is a star in the southern constellation of Grus (it once belonged to the Ptolemaic constellation Piscis Austrinus). With an apparent visual magnitude of 3.0,[2] it is the third-brightest star in Grus. Based upon parallax measurements, this star is located at a distance of roughly 211 light-years (65 parsecs) from the Sun.[1]

Nomenclature

γ Gruis (Latinised to Gamma Gruis) is the system's Bayer designation.

It bore the traditional Arabic name Al Dhanab, from the Arabic الذنب al-dhanab "the tail" (of the Southern Fish)[14]when it was still part of Piscis Austrinus with the Bayer designation κ Piscis Austrini (Kappa Piscis Austrini). In 2016, the IAU organized a Working Group on Star Names (WGSN)[15] to catalog and standardize proper names for stars. The WGSN approved the name Aldhanab for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[13]

In Chinese, 敗臼 (Bài Jiù), meaning Decayed Mortar, refers to an asterism consisting of Gamma Gruis, Lambda Gruis, Gamma Piscis Austrini and 19 Piscis Austrini.[16] Consequently, the Chinese name for Gamma Gruis itself is 敗臼一 (Bài Jiù yī, English: the First Star of Decayed Mortar.)[17]

Properties

Analysis of the spectrum by N. Houk in 1979 shows it to match a stellar classification of B8 III,[3] with the luminosity class of III indicating this is a giant star that has exhausted the supply of hydrogen at its core and evolved away from the main sequence. R. O. Gray and R. F. Garrison in 1989 found a less evolved class of B8IV-Vs.[4] The luminosity of Gamma Gruis is around 390 times that of the Sun, with a significant portion of the energy emission being in the ultraviolet.[18] Its outer envelope has an effective temperature of 12,520 K,[9] which gives the star a blue-white hue. Gamma Gruis is rotating relatively rapidly with a projected rotational velocity of 57 km s−1.[11] By way of comparison, the Sun has an azimuthal velocity along its equator of just 2 km s−1.

Based upon analysis of data collected during the Hipparcos mission, this star may have a proper motion companion that is causing gravitational perturbation of Gamma Gruis.[19]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V 
  2. ↑ 2.0 2.1 2.2 2.3 Gutierrez-Moreno, Adelina et al. (1966). "A System of photometric standards". Publications of the Department of Astronomy University of Chile (Publicaciones Universidad de Chile, Department de Astronomy) 1: 1–17. Bibcode: 1966PDAUC...1....1G. 
  3. ↑ 3.0 3.1 Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 3, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode: 1982mcts.book.....H 
  4. ↑ 4.0 4.1 Gray, R. O.; Garrison, R. F. (1989), "The late A-type stars – Refined MK classification, confrontation with Stromgren photometry, and the effects of rotation", Astrophysical Journal Supplement Series 70: 623, doi:10.1086/191349, Bibcode: 1989ApJS...70..623G. 
  5. ↑ Wilson, R. E. (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.C. Publication (Carnegie Institute of Washington D.C.). Bibcode: 1953GCRV..C......0W. 
  6. ↑ 6.0 6.1 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.0 7.1 7.2 David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal 804 (2): 146, doi:10.1088/0004-637X/804/2/146, Bibcode: 2015ApJ...804..146D. 
  8. ↑ Underhill, A. B. et al. (November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars", Monthly Notices of the Royal Astronomical Society 189 (3): 601–605, doi:10.1093/mnras/189.3.601, Bibcode: 1979MNRAS.189..601U 
  9. ↑ 9.0 9.1 Zorec, J. et al. (July 2009), "Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into Teff", Astronomy and Astrophysics 501 (1): 297–320, doi:10.1051/0004-6361/200811147, Bibcode: 2009A&A...501..297Z 
  10. ↑ Barraza, L. F.; Gomes, R. L.; Messias, Y. S.; Leão, I. C.; Almeida, L. A.; Janot-Pacheco, E.; Brito, A. C.; Brito, F. A. C. et al. (2022). "Rotation Signature of TESS B-type Stars. A Comprehensive Analysis". The Astrophysical Journal 924 (2): 117. doi:10.3847/1538-4357/ac3335. Bibcode: 2022ApJ...924..117B. 
  11. ↑ 11.0 11.1 Royer, F. et al. (2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i in the northern hemisphere", Astronomy and Astrophysics 393 (3): 897–911, doi:10.1051/0004-6361:20020943, Bibcode: 2002A&A...393..897R 
  12. ↑ "gam Gru". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=gam+Gru. 
  13. ↑ 13.0 13.1 "Naming Stars". IAU.org. https://www.iau.org/public/themes/naming_stars/. 
  14. ↑ Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York, NY: Dover Publications Inc., p. 238, ISBN 0-486-21079-0 
  15. ↑ "IAU Working Group on Star Names (WGSN)". https://www.iau.org/science/scientific_bodies/working_groups/280/. 
  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 5 日
  18. ↑ Kaler, James B., "AL DHANAB (Gamma Gruis)", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/aldhanab.html, retrieved 2012-02-11 
  19. ↑ Frankowski, A.; Jancart, S.; Jorissen, A. (March 2007), "Proper-motion binaries in the Hipparcos catalogue. Comparison with radial velocity data", Astronomy and Astrophysics 464 (1): 377–392, doi:10.1051/0004-6361:20065526, Bibcode: 2007A&A...464..377F 



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