Gamma Gruis

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Gamma Gruis
Diagram showing star positions and boundaries of the Grus constellation and its surroundings
Cercle rouge 100%.svg
Location of γ Gruis (circled) near the center
Observation data
Epoch J2000      Equinox J2000
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]
U−B color index –0.307[2]
B−V color index –0.121[2]
Astrometry
Radial velocity (Rv)–2.1[4] 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[5]
Details
Mass3.06[6] M
Radius4.5[7] R
Luminosity373[5] L
Surface gravity (log g)3.79[6] cgs
Temperature12,520[8] K
Rotational velocity (v sin i)57[9] km/s
Age75[6] Myr
Other designations
γ Gru, CD−37° 9119, FK5 822, GC 30640, HD 207971, HIP 108085, HR 8353, SAO 213374[10]
Database references
SIMBADdata

Gamma Gruis (γ Gruis, abbreviated Gam Gru, γ Gru), formally named Aldhanab /ˈældənæb/,[11] 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[edit]

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).[12] In 2016, the IAU organized a Working Group on Star Names (WGSN)[13] 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.[11]

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.[14] Consequently, the Chinese name for Gamma Gruis itself is 敗臼一 (Bài Jiù yī, English: the First Star of Decayed Mortar.)[15]

Properties[edit]

Analysis of the spectrum 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; 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.[16] Its outer envelope has an effective temperature of 12,520 K,[8] which gives the star a blue-white hue. Gamma Gruis is rotating relatively rapidly with a projected rotational velocity of 57 km s−1.[9] 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.[17]

See also[edit]

References[edit]

  1. ^ a b c d e f 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
  2. ^ a b c d Gutierrez-Moreno, Adelina; et al. (1966). "A System of photometric standards". 1. Publicaciones Universidad de Chile, Department de Astronomy: 1–17. Bibcode:1966PDAUC...1....1G.
  3. ^ a b 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. ^ Wilson, R. E. (1953). General Catalogue of Stellar Radial Velocities. Carnegie Institute of Washington D.C. Bibcode:1953GCRV..C......0W.
  5. ^ a b 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.
  6. ^ a b c 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, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146.
  7. ^ 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: 601–605, Bibcode:1979MNRAS.189..601U, doi:10.1093/mnras/189.3.601
  8. ^ a b 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, arXiv:0903.5134, Bibcode:2009A&A...501..297Z, doi:10.1051/0004-6361/200811147
  9. ^ a b 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, arXiv:astro-ph/0205255, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943
  10. ^ "gam Gru". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2007-03-30.
  11. ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
  12. ^ 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
  13. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  14. ^ ‹See Tfd›(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.
  15. ^ ‹See Tfd›(in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 5 日
  16. ^ Kaler, James B., "AL DHANAB (Gamma Gruis)", Stars, University of Illinois, retrieved 2012-02-11
  17. ^ 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, arXiv:astro-ph/0612449, Bibcode:2007A&A...464..377F, doi:10.1051/0004-6361:20065526