Gamma Cancri

Gamma Cancri, or γ Cancri, is a star in the northern constellation of Cancer. It is formally named Asellus Borealis /əˈsɛləs bɒriˈælɪs/, the traditional name of the system.[12] Based on parallax measurements, it is located at a distance of approximately 181 light years from the Sun. The star is drifting further away with a radial velocity of 29 km/s.[5] In 1910 this star was reported to be a spectroscopic binary by O. J. Lee,[13] but is now considered a single star.[14][15] Since it is near the ecliptic, it can be occulted by the Moon[16] and, very rarely, by planets.

Gamma Cancri
Location of γ Cancri (circled)
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) 4.673[2]
Characteristics
Spectral type A1IV[3]
U−B color index +0.03[4]
B−V color index +0.010[2]
Astrometry
Radial velocity (Rv)28.7[5] km/s
Proper motion (μ) RA: −103.51[1] mas/yr
Dec.: −39.48[1] mas/yr
Parallax (π)18.00 ± 0.21 mas[1]
Distance181 ± 2 ly
(55.6 ± 0.6 pc)
Absolute magnitude (MV)+1.1[6]
Details
Mass2.18[7] M☉
Radius2.5[8] R☉
Luminosity36[9] L☉
Surface gravity (log g)4.17[7] cgs
Temperature9,108[9] K
Rotational velocity (v sin i)86±6[10] km/s
Age171[7] Myr
Other designations
Asellus Borealis, γ Cnc, Gamma Cnc, 43 Cnc, BD+21° 1895, FK5 1228, GC 11982, HD 74198, HIP 42806, HR 3449, SAO 80378, CCDM 08433+2128[11]
Database references
SIMBADdata

Nomenclature

γ Cancri (Latinised to Gamma Cancri) is the star's Bayer designation. It bore the traditional name Asellus Borealis (Latin for "northern donkey").[17] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[18] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[19] It approved the name Asellus Borealis for the star on 6 November 2016 and it is now so included in the List of IAU-approved Star Names.[12] Together with Delta Cancri, it formed the Aselli, flanking Praesepe.[20]

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.[21] Gamma Cancri itself is known as the third star of Ghost (Chinese: 鬼宿三; pinyin: Guǐ Xiù sān).[22]

Properties

Gamma Cancri presents as a white A-type subgiant with an apparent magnitude of +4.67.[3] The star is an estimated 171[7] million years old and is spinning with a projected rotational velocity of 86 km/s.[10] It has 2.18[7] times the mass of the Sun and shines with a luminosity approximately 36 times greater at an effective temperature of 9108 K.[9]

It has been included as a member of the Hyades Stream based on its distance, space motion, and likely age.[23]

References
  1. 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. S2CID 18759600.
  2. 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, S2CID 119257644.
  3. Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement. 95: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182.
  4. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  5. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode:1953GCRV..C......0W.
  6. 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.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. 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. S2CID 33401607. Vizier catalog entry
  8. 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. S2CID 425754.
  9. 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. S2CID 118665352.
  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. S2CID 14070763.
  11. "gam Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 8 April 2015.
  12. "Naming Stars". IAU.org. Retrieved 16 December 2017.
  13. Lee, Oliver J. (November 1910). "Measures on nineteen new spectroscopic binaries". Astrophysical Journal. 32: 300–308. Bibcode:1910ApJ....32..300L. doi:10.1086/141806.
  14. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
  15. De Rosa, R. J.; et al. (July 2011). "The Volume-limited A-Star (VAST) survey - I. Companions and the unexpected X-ray detection of B6-A7 stars". Monthly Notices of the Royal Astronomical Society. 415 (1): 854–866. arXiv:1103.4363. Bibcode:2011MNRAS.415..854D. doi:10.1111/j.1365-2966.2011.18765.x. S2CID 84181878.
  16. Schmidtke, P. C.; Africano, J. L. (January 2011). "KPNO Lunar Occultation Summary. III". The Astronomical Journal. 141 (1): 7. Bibcode:2011AJ....141...10S. doi:10.1088/0004-6256/141/1/10. S2CID 120313180. 10.
  17. Dixon-Kennedy, Mike (1998), Encyclopedia of Greco-Roman Mythology, ABC-CLIO, p. 51, ISBN 9781576070949
  18. IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
  19. "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
  20. Richard H. Allen (28 February 2013). Star Names: Their Lore and Meaning. Courier Corporation. ISBN 978-0-486-13766-7.
  21. 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.
  22. 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
  23. Eggen, Olin J. (October 1992). "The Hyades Supercluster in FK5". Astronomical Journal. 104: 1482. Bibcode:1992AJ....104.1482E. doi:10.1086/116333.
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