Beta Gruis

Beta Gruis


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])
Characteristics
Spectral type M5 III[4]
U−B color index +1.757[2]
B−V color index +1.620[2]
Variable type SRb[3]
Astrometry
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
Distance177 ± 4 ly
(54 ± 1 pc)
Details
Mass2.4[6] M☉
Radius180[7] R☉
Luminosity2,500[7] L☉
Surface gravity (log g)0.4[7] cgs
Temperature3,480[8] K
Metallicity [Fe/H]0.0[7] dex
Other designations
Bet Gru, CD−47 14308, FK5 856, HR 8636, HD 214952, HIP 112122, SAO 231258.[9]
Database references
SIMBADdata

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.[10]

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,[8] 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.[6]

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.[11]

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
  2. 1 2 3 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. 1 2 3 4 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, Bibcode:1978mcts.book.....H
  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. 1 2 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
  7. 1 2 3 4 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
  8. 1 2 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
  9. ↑ "V* bet Gru -- Variable Star", SIMBAD (Centre de Données astronomiques de Strasbourg), retrieved 2010-01-05
  10. ↑ 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
  11. ↑ "Astronomy News". December 16, 2001.

External links

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

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