Alpha Cancri

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Alpha Cancri
Cancer constellation map.png
α Cancri in the constellation Cancer
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cancer
Right ascension  08h 58m 29.2217s[1]
Declination +11° 51′ 27.723″[1]
Apparent magnitude (V) 4.20 to 4.27[2]
Spectral type A5m[1]
U−B color index +0.15[3]
B−V color index +0.14[3]
R−I color index +0.04[3]
Radial velocity (Rv)−13.8 ± 2[1] km/s
Proper motion (μ) RA: 36.109[4] mas/yr
Dec.: −24.669[4] mas/yr
Parallax (π)19.8724 ± 0.4129[4] mas
Distance164 ± 3 ly
(50 ± 1 pc)
Absolute magnitude (MV)0.46[5]
Aa + Ab
Mass2.10[6] M
Luminosity50.55[7] L
Temperature7,943[8] K
Rotational velocity (v sin i)75[9] km/s
Mass0.38[6] M
Other designations
Acubens, Sertan, Sartan,[3] α Cnc, Alpha Cancri, Alpha Cnc, 65 Cancri, 65 Cnc, ADS 7115 A, BD+12 1948, CCDM J08585+1151A, FK5 337, GC 12406, HD 76756, HIP 44066, HR 3572, IDS 08530+1215 A, PPM 125972, SAO 98267[1]
Database references

Alpha Cancri (α Cancri, abbreviated Alpha Cnc, α Cnc), also named Acubens /ˈækjuːbɛnz/,[10] is a star system in the constellation of Cancer.


α Cancri (Latinised to Alpha Cancri) is the star's Bayer designation.

The traditional name Acubens (Açubens) is derived from the Arabic الزبانىal zubanāh, "the claws" [11] A second name, Sertan /ˈsɜːrtæn/, derives from the Arabic al-saraṭān 'the crab'. The International Astronomical Union Working Group on Star Names (WGSN) choose 'Acubens' as the proper name for this star.[12]


Alpha Cancri is a fourth-magnitude star with an apparent magnitude of 4.20, making it barely visible to the naked eye under good lighting conditions. Nevertheless, it is 23 times more luminous than the Sun. Its stellar classification is A5m. The distance of Alpha Cancri calculated from the Gaia Data Release 2 parallax is roughly 50 parsecs from Earth, or approximately 164 light years away.

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

Star system[edit]

The primary component, α Cancri A, is a white A-type main sequence dwarf with an apparent magnitude of +4.26. Its companion, α Cancri B, is an eleventh magnitude star. In the year 1836, its position angle was observed at 325 degrees with a separation from the main star α Cancri A of 11.3 arcseconds.[13][14]

From studying its light curve during occultation, it is thought that α Cancri A may itself be a close binary, consisting of two stars with similar brightness and a separation of 0.1 arcseconds.[3]

In modern culture[edit]

USS Acubens (AKS-5) was a United States navy ship.


  1. ^ a b c d e "alf Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2009-09-20.
  2. ^ NSV 4327, database entry, New Catalogue of Suspected Variable Stars, the improved version, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line October 20, 2009.
  3. ^ a b c d e HR 3572, 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 October 20, 2009.
  4. ^ a b c Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  5. ^ 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.
  6. ^ a b Tokovinin, A. A. (1997). "MSC - a catalogue of physical multiple stars". Astronomy and Astrophysics Supplement Series. 124: 75–84. Bibcode:1997A&AS..124...75T. doi:10.1051/aas:1997181.
  7. ^ 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. arXiv:1208.2037. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x.
  8. ^ a b Baines, Ellyn K.; Armstrong, J. Thomas; Schmitt, Henrique R.; Zavala, R. T.; Benson, James A.; Hutter, Donald J.; Tycner, Christopher; Van Belle, Gerard T. (2018). "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer". The Astronomical Journal. 155 (1): 30. Bibcode:2018AJ....155...30B. doi:10.3847/1538-3881/aa9d8b.
  9. ^ 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 in the northern hemisphere". Astronomy and Astrophysics (PDF). 393 (3): 897–911. arXiv:astro-ph/0205255. Bibcode:2002A&A...393..897R. doi:10.1051/0004-6361:20020943.
  10. ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
  11. ^ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Cancer
  12. ^ "Naming Stars". International Astronomical Union. Retrieved 2018-11-04.
  13. ^ "CCDM (Catalog of Components of Double & Multiple stars (Dommanget+ 2002)". VizieR. Centre de Données astronomiques de Strasbourg. Retrieved 2010-05-13.
  14. ^ "Acubens". Alcyone Bright Star Catalogue. Retrieved 2010-05-13.

External links[edit]

  • Jim Kaler's Stars, University of Illinois: Acubens