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β Corvi
Corvus constellation map.svg
Red circle.svg
Location of β Corvi (circled)
Observation data
Epoch J2000.0       Equinox J2000.0 ( ICRS)
Constellation Corvus
Right ascension 12h 34m 23.23484s [1]
Declination −23° 23′ 48.3374″ [1]
Apparent magnitude (V) 2.647 [2]
Spectral type G5 II [3]
U−B color index +0.586 [2]
B−V color index +0.898 [2]
R−I color index +0.44 [4]
Radial velocity (Rv)−7.6 [5] km/s
Proper motion (μ) RA: +1.11 [1]  mas/ yr
Dec.: −56.56 [1]  mas/ yr
Parallax (π)22.39 ± 0.18  mas [1]
Distance146 ± 1  ly
(44.7 ± 0.4  pc)
Absolute magnitude (MV)–0.61 [6]
Mass3.7±0.1 [3]  M
Radius16 [7]  R
Luminosity164 [8]  L
Surface gravity (log g)2.52±0.03 [3]  cgs
Temperature5,100±80 [3]  K
Metallicity [Fe/H]–0.01 [6]  dex
Rotational velocity (v sin i)8 [9] km/s
Age206 [3]  Myr
Other designations
Kraz, β Crv, Beta Corvi, Beta Crv, 9 Corvi, 9 Crv, BD−22 3401, CD−22 3401, −22 9505, CPD−22 5388, FK5 471, GC 17133, HD 109379, HIP 61359, HR 4786, SAO 180915, PPM 260512 [4] [10]
Database references

Beta Corvi or β Corvi, officially named Kraz ( /ˈkræz/), [11] is the second-brightest star in the southern constellation of Corvus with an apparent visual magnitude of 2.647. [2] Based on parallax measurements obtained during the Hipparcos mission, it is about 146 light-years (45 parsecs) distant from the Sun.


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

In a 1951 publication, Atlas Coeli ( Skalnate Pleso Atlas of the Heavens) by Czech astronomer Antonín Bečvář, it bore the name Kraz, whose origin and meaning remain unknown. [12] [13] [14] 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 Kraz for this star on 1 June 2018 and it is now so included in the List of IAU-approved Star Names. [11]

In Chinese, 軫宿 (Zhěn Sù), meaning Chariot (asterism), refers to an asterism consisting of Beta, Gamma, Epsilon and Delta Corvi. [16] Consequently, Beta Corvi itself is known as 軫宿四 (Zhěn Sù sì, English: the Fourth Star of Chariot). [17]


Beta Corvi has about 3.7 times the Sun's mass and is roughly 206 million years old, [3] which is old enough for a star of this mass to consume the hydrogen at its core and evolve away from the main sequence. The stellar classification is G5 II, [3] with the luminosity class of 'II' indicating this is a bright giant. The effective temperature of the star's outer envelope is about 5,100 K, [3] which produces a yellow hue common to G-type stars. [18]

The measured angular diameter of this star is 3.30 ± 0.17 mas. [7] At an estimated distance of 146 light-years (45 parsecs), [1] this yields a physical size of about 16 times the radius of the Sun. [13] [19] Because of the star's mass and radius, it is emitting about 164 times the luminosity of the Sun. [8] The abundance of elements other than hydrogen or helium, what astronomers term metallicity, is similar to the proportions in the Sun. [6]

This is a variable star that ranges in apparent visual magnitude from a low of 2.66 to a high of 2.60. [20]

See also


  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. S2CID  18759600.
  2. ^ a b c d 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. ^ a b c d e f g h Lyubimkov, Leonid S.; et al. (February 2010). "Accurate fundamental parameters for A-, F- and G-type Supergiants in the solar neighbourhood". Monthly Notices of the Royal Astronomical Society. 402 (2): 1369–1379. arXiv: 0911.1335. Bibcode: 2010MNRAS.402.1369L. doi: 10.1111/j.1365-2966.2009.15979.x. S2CID  119096173.
  4. ^ a b HR 4786, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 9, 2008.
  5. ^ Evans, D. S. (June 20–24, 1966). Batten, Alan Henry; Heard, John Frederick (eds.). "The Revision of the General Catalogue of Radial Velocities". Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. 30: 57. Bibcode: 1967IAUS...30...57E.
  6. ^ a b c Takeda, Yoichi; Sato, Bun'ei; Murata, Daisuke (August 2008), "Stellar Parameters and Elemental Abundances of Late-G Giants", Publications of the Astronomical Society of Japan, 60 (4): 781–802, arXiv: 0805.2434, Bibcode: 2008PASJ...60..781T, doi: 10.1093/pasj/60.4.781, S2CID  16258166
  7. ^ a b Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode: 2005A&A...431..773R, doi: 10.1051/0004-6361:20042039
  8. ^ a b Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics, 352: 495–507, Bibcode: 1999A&A...352..495M
  9. ^ Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago. 239 (1): 1. Bibcode: 1970CoAsi.239....1B.
  10. ^ SV* ZI 946 -- Variable Star, database entry, SIMBAD. Accessed on line September 9, 2008.
  11. ^ a b "Naming Stars". Retrieved 18 June 2018.
  12. ^ Kunitzch, Paul; Smart, Tim (2006) [1986]. A Dictionary of Modern Star Names: A Short Guide to 254 Star Names and Their Derivations. Cambridge, Massachusetts: Sky Publishing Corporation. p. 62. ISBN  978-1-931559-44-7.
  13. ^ a b Kaler, James B., "KRAZ (Beta Corvi)", Stars, University of Illinois, retrieved 2012-12-28
  14. ^ Falkner, David E. (2011), The Mythology of the Night Sky: An Amateur Astronomer's Guide to the Ancient Greek and Roman Legends, Patrick Moore's Practical Astronomy, Springer, p. 81, ISBN  978-1-4614-0136-0
  15. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  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) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2011-01-29 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  18. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2012-03-18, retrieved 2012-01-16
  19. ^ Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN  3-540-29692-1. The radius (R*) is given by:
  20. ^ Kukarkin, B. V.; et al. (1981), "Nachrichtenblatt der Vereinigung der Sternfreunde e.V. (Catalogue of suspected variable stars)", Nachrichtenblatt der Vereinigung der Sternfreunde, Moscow: Academy of Sciences USSR Shternberg, Bibcode: 1981NVS...C......0K