Gamma Cancri

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Gamma Cancri
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cancer
Right ascension  08h 43m 17.14820s[1]
Declination +21° 28′ 06.6008″[1]
Apparent magnitude (V) 4.652[2]
Spectral type A1IV[2]
U−B color index +0.03[3]
B−V color index +0.00[3]
Radial velocity (Rv)28.7[4] km/s
Proper motion (μ) RA: −103.51[1] mas/yr
Dec.: −39.48[1] mas/yr
Parallax (π)18.00 ± 0.21[1] mas
Distance181 ± 2 ly
(55.6 ± 0.6 pc)
Absolute magnitude (MV)+1.1[5]
Mass2.18[6] M
Radius2.5[7] R
Luminosity36[8] L
Surface gravity (log g)4.17[6] cgs
Temperature8,800[9] K
Rotational velocity (v sin i)86 ± 6[10] km/s
Age171[6] Myr
Other designations
Asellus Borealis, γ Cnc, 43 Cnc, BD+21° 1895, FK5 1228, GC 11982, HD 74198, HIP 42806, HR 3449, SAO 80378, CCDM 08433+2128
Database references

Gamma Cancri (γ Cancri, abbreviated Gamma Cnc, γ Cnc) is a multiple star system in the constellation of Cancer.

It consists of a spectroscopic binary, designated Gamma Cancri A, and a single companion star, Gamma Cancri B. A's two components are themselves designated Gamma Cancri Aa (formally named Asellus Borealis /əˈsɛləs bɒriˈælɪs/, the traditional name of the system)[11] and Ab.

Since it is near the ecliptic, it can be occulted by the Moon and, very rarely, by planets.


γ Cancri (Latinised to Gamma Cancri) is the system's Bayer designation. The designations of the two constituents as Gamma Cancri A and B, and those of A's components - Gamma Cancri Aa and Ab - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[12]

It bore the traditional name Asellus Borealis (Latin for "northern little donkey").[citation needed] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[13] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[14] It approved the name Asellus Borealis for the component Gamma Cancri Aa on 6 November 2016 and it is now so included in the List of IAU-approved Star Names.[11] Together with Delta Cancri, it formed the Aselli, flanking Praesepe.[15]

In Chinese astronomy, Ghost (Chinese: 鬼宿; pinyin: Guǐ Xiù) refers to an asterism consisting of Theta Cancri, Eta Cancri, Gamma Cancri and Delta Cancri.[16] Gamma Cancri itself is known as the third star of Ghost (Chinese: 鬼宿三; pinyin: Guǐ Xiù sān).[17]


Gamma Cancri A presents as a white A-type subgiant with an apparent magnitude of +4.67.[2] Located around 181 light-years from the Sun, it shines with a luminosity approximately 36 times greater and has a surface temperature of 9108 K.[8]


  1. ^ a b c d e van Leeuwen, F. (2007). "Validation of the New Hipparcos Reduction". Astronomy and Astrophysics. 474 (2): 653–64. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. ^ a b c "gam Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 April 2015.
  3. ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  4. ^ Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode:1953GCRV..C......0W.
  5. ^ Eggen, O. J.; Iben, Icko, Jr. (1988). "Starbursts, binary stars, and blue stragglers in local superclusters and groups. I - The very young disk and young disk populations". Astronomical Journal. 96: 635–669. Bibcode:1988AJ.....96..635E. doi:10.1086/114834.CS1 maint: multiple names: authors list (link)
  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. Vizier catalog entry
  7. ^ Pasinetti Fracassini, L. E.; et al. (2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy & Astrophysics. 367 (2): 521–24. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451.
  8. ^ a b McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (2012). "Fundamental Parameters and Infrared Excesses of Hipparcos Stars". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–57. arXiv:1208.2037. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x.
  9. ^ Theodossiou, E.; Danezis, E. (1991). "The stellar temperature scale for stars of spectral types from O8 to F6 and the standard deviation of the MK spectral classification". Astrophysics and Space Science. 183 (1): 91–115. Bibcode:1991Ap&SS.183...91T. doi:10.1007/BF00643019.
  10. ^ Royer, F.; Grenier, S.; Baylac, M.-O.; Gómez, A. E.; Zorec, J. (2002). "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i". Astronomy and Astrophysics. 393: 897–911. arXiv:astro-ph/0205255. Bibcode:2002A&A...393..897R. doi:10.1051/0004-6361:20020943.
  11. ^ a b "Naming Stars". Retrieved 16 December 2017.
  12. ^ Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  13. ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
  14. ^ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
  15. ^ Richard H. Allen (28 February 2013). Star Names: Their Lore and Meaning. Courier Corporation. ISBN 978-0-486-13766-7.
  16. ^ 陳久金 (2005). Zhōngguó Xīngzuò Shénhuà 中國星座神話 [Chinese Constellation Mythology]. 台灣古籍出版有限公司. p. 394. ISBN 978-986-7332-25-7.
  17. ^ 亮星中英對照表 [English-Chinese Glossary of Bright Stars]. Hong Kong Space Museum (in Chinese). Retrieved February 3, 2018. Asellus Borealis