Alpha Cancri

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Alpha Cancri
Cancer constellation map.png
Acubens is the α star in the "crab"
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: 41.45[1] mas/yr
Dec.: −29.22[1] mas/yr
Parallax (π)18.79 ± 0.99[4] mas
Distance174 ± 9 ly
(53 ± 3 pc)
Absolute magnitude (MV)0.46[5]
Mass2[6] M
Radius0.998[7] R
Luminosity23[6] L
Rotational velocity (v sin i)75[8] km/s
Other designations
Acubens, Sertan, Sartan, 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][3]
Database references

Alpha Cancri (α Cancri, abbreviated Alpha Cnc, α Cnc), also named Acubens,[9] 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" [10] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[11] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[12] included a table of the first two batches of names approved by the WGSN; which included Acubens for this star.


Acubens 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 Hipparcos mission estimated the distance of Acubens to be roughly 53 parsecs[4] from Earth, or approximately 174 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.

See also[edit]


  1. ^ a b c d e f g "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 Perryman, M. A. C.; et al. (1997), "The Hipparcos Catalogue", Astronomy & Astrophysics, 323: L49–L52, Bibcode:1997A&A...323L..49P
  5. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971 [astro-ph.GA], Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. Cite uses deprecated parameter |class= (help)
  6. ^ a b Professor James B. (Jim) Kaler. "ACUBENS (Alpha Cancri)". University of Illinois. Retrieved 2010-05-13.
  7. ^ HD 76756, database entry, Catalog of Apparent Diameters and Absolute Radii of Stars (CADARS), 3rd edition, L. E. Pasinetti-Fracassini, L. Pastori, S. Covino, and A. Pozzi, CDS ID II/224. Accessed on line October 20, 2009.
  8. ^ 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.
  9. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
  10. ^ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Cancer
  11. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  12. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  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