Beta Gruis

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Beta Gruis
Grus constellation map.svg
Red circle.svg

Location of β Gruis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Grus
Right ascension 22h 42m 40.05027s[1]
Declination −46° 53′ 04.4752″[1]
Apparent magnitude (V) 2.146[2] (2.0 - 2.3[3])
Spectral type M5 III[4]
U−B color index +1.757[2]
B−V color index +1.620[2]
Variable type SRb[3]
Radial velocity (Rv) +1.6[5] km/s
Proper motion (μ) RA: +135.16[1] mas/yr
Dec.: −4.38[1] mas/yr
Parallax (π) 18.43 ± 0.42[1] mas
Distance 177 ± 4 ly
(54 ± 1 pc)
Absolute magnitude (MV) −1.61±0.052[6]
Mass 2.4[7] M
Radius 180[8] R
Luminosity 2,500[8] L
Surface gravity (log g) 0.4[8] cgs
Temperature 3,480[9] K
Metallicity [Fe/H] 0.0[8] dex
Other designations
Bet Gru, CD−47 14308, FK5 856, HR 8636, HD 214952, HIP 112122, SAO 231258.[10]
Database references

Beta Gruis (β Gruis, β Gru) 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: it, with α, δ, θ. ι, and λ Gru, belonged to Piscis Austrinus in medieval Arabic astronomy.[11]

This is a red giant star[3] with an estimated mass of about 2.4 times that of the Sun and a surface temperature of approximately 3,480 K,[9] 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 2,500 times that of the Sun, and it has estimated 180 times the Sun's radius.[7]

Beta Gruis is a type 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.[3]

Beta Gruis played a crucial part in Perth Observatory's tracking of comet 2000 WM1 LINEAR in December 2001.[12]


  1. ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357 
  2. ^ a b c Gutierrez-Moreno, Adelina; et al. (1966), "A System of photometric standards", Publ. Dept. Astron. Univ. Chile, Publicaciones Universidad de Chile, Department de Astronomy, 1: 1–17, Bibcode:1966PDAUC...1....1G 
  3. ^ a b c d 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 
  4. ^ Houk, Nancy (1978), "Michigan catalogue of two-dimensional spectral types for the HD stars", Ann Arbor : Dept. of Astronomy, Ann Arbor: Dept. of Astronomy, University of Michigan, 2, 
  5. ^ Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veröff. Astron. Rechen-Inst. Heidelb, Astronomisches Rechen-Institut Heidelberg, 35 (35), Bibcode:1999VeARI..35....1W 
  6. ^ Park, Sunkyung; et al. (2013), "Wilson-Bappu Effect: Extended to Surface Gravity", The Astronomical Journal, 146 (4): 73, Bibcode:2013AJ....146...73P, arXiv:1307.0592Freely accessible, doi:10.1088/0004-6256/146/4/73. 
  7. ^ a b 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 
  8. ^ a b c d 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 
  9. ^ a b 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 
  10. ^ "V* bet Gru -- Variable Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2010-01-05 
  11. ^ Allen, R. H. (1963), Star Names: Their Lore and Meaning (rep ed.), New York, NY: Dover Publications Inc., p. 238, ISBN 0-486-21079-0 
  12. ^ "Astronomy News". December 16, 2001. Archived from the original on October 25, 2007. 

External links[edit]

Coordinates: Sky map 22h 42m 40.1s, −46° 53′ 05″