Astronomy:Alpha Cancri

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Short description: Star system in the constellation Cancer
α Cancri
α Cancri, circled, is the bottom left star in the "crab".
Observation data
Equinox J2000.0]] (ICRS)
Constellation Cancer[1]
Right ascension  08h 58m 29.2042s[2]
Declination +11° 51′ 27.649″[2]
Apparent magnitude (V) 4.20 to 4.27[3]
Characteristics
Spectral type kA7VmF0/2III/IVSr[4]
U−B color index +0.15[5]
B−V color index +0.14[5]
R−I color index +0.04[5]
Astrometry
Radial velocity (Rv)−12.1±0.8[6] km/s
Proper motion (μ) RA: 42.181[2] mas/yr
Dec.: −31.160[2] mas/yr
Parallax (π)18.3304 ± 0.3216[2] mas
Distance178 ± 3 ly
(54.6 ± 1.0 pc)
Absolute magnitude (MV)0.46[1]
Details
A
Mass2.10[7] M☉
Radius3.655[8] R☉
Luminosity49[8] L☉
Surface gravity (log g)3.73[9] cgs
Temperature7,943[9] K
Rotational velocity (v sin i)75[10] km/s
B
Mass0.38[7] M☉
Other designations
Acubens, Sertan, Sartan[5], α Cnc, Alpha Cancri, Alpha Cnc, 65 Cancri, 65 Cnc, BD+12 1948, FK5 337, GC 12406, HD 76756, HIP 44066, HR 3572, SAO 98267, PPM 125972, ADS 7115 A, CCDM J08585+1151A[11]
Database references
SIMBADdata
B

Alpha Cancri is a star system in the northern constellation of Cancer. Its name is a Bayer designation that is Latinized from α Cancri, and abbreviated Alpha Cnc or α Cnc. The primary component has the proper name Acubens, pronounced /ˈækjuːbɛnz/.[12] It forms a fourth-magnitude star with an apparent magnitude of 4.20, making it barely visible to the naked eye under good viewing conditions. Based on parallax measurements, it is located at a distance of 178 light-years (55 pc) from the Sun, but is drifting closer with a radial velocity of −12 km/s.[6] Since it is near the ecliptic, it can be occulted by the Moon.[13]

Properties

The primary component, α Cancri A, has a stellar classification of kA7VmF0/2III/IVSr, indicating an Am star with calcium K-lines similar to an A7 main sequence star and hydrogen lines more like an F0 giant or subgiant star. It is a white A-type main-sequence star with an apparent magnitude of +4.26. The star has 2.10[7] times the mass of the Sun and 3.7[8] times the Sun's radius. It has a high rate of spin, showing a projected rotational velocity of 75 km/s.[10] The star is radiating 49 times the luminosity of the Sun from its photosphere at an effective temperature of 7,943 K.[9]

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.[14][15] α Cancri A may itself be a close binary, consisting of two stars with similar brightness and a separation of 0.1 arcsecond, though this is questioned.[5] Indeed, a light curve generated during a 2014 lunar occultation failed to demonstrate a close companion.[13]

Nomenclature

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

The traditional name Acubens (Açubens) is derived from the Arabic الزبانى al zubanāh, 'the claws'.[16] 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 the primary component of this star.[17]

In modern culture

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

References

  1. ↑ 1.0 1.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A  XHIP record for this object at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  3. ↑ "NSV 4327, database entry". New Catalogue of Suspected Variable Stars, the improved version. Moscow, Russia: Sternberg Astronomical Institute. http://www.sai.msu.su/groups/cluster/gcvs/gcvs/nsv/nsv.dat. 
  4. ↑ Sreedhar Rao, S.; Abhyankar, K. D. (1991). "MK morphological study of AM stars at 66 A/Mm". Journal of Astrophysics and Astronomy 12 (2): 133. doi:10.1007/BF02709302. Bibcode: 1991JApA...12..133S. 
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Hoffleit, D.; Warren, Jr., W. H.. "HR 3572, database entry". The Bright Star Catalogue. Centre de Données astronomiques de Strasbourg. http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=V/50/catalog&recno=3572. 
  6. ↑ 6.0 6.1 Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. Bibcode: 2006AstL...32..759G. 
  7. ↑ 7.0 7.1 7.2 Tokovinin, A. A. (1997). "MSC - a catalogue of physical multiple stars". Astronomy and Astrophysics Supplement Series 124: 75–84. doi:10.1051/aas:1997181. Bibcode: 1997A&AS..124...75T. 
  8. ↑ 8.0 8.1 8.2 McDonald, I. et al. (October 2017). "Fundamental parameters and infrared excesses of Tycho-Gaia stars". Monthly Notices of the Royal Astronomical Society 471 (1): 770–791. doi:10.1093/mnras/stx1433. ISSN 0035-8711. Bibcode: 2017MNRAS.471..770M.  Acubens' database entry at VizieR.
  9. ↑ 9.0 9.1 9.2 Baines, Ellyn K. et al. (2018). "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer". The Astronomical Journal 155 (1): 30. doi:10.3847/1538-3881/aa9d8b. Bibcode: 2018AJ....155...30B. 
  10. ↑ 10.0 10.1 Royer, F. et al. (2002). "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i in the northern hemisphere". Astronomy and Astrophysics 393 (3): 897–911. doi:10.1051/0004-6361:20020943. Bibcode: 2002A&A...393..897R. 
  11. ↑ "alf Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=alf+Cnc. 
  12. ↑ 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 Publishing. ISBN 978-1-931559-44-7. 
  13. ↑ 13.0 13.1 Richichi, A. et al. (November 2014). "First Lunar Occultation Results from the 2.4 m Thai National Telescope Equipped with ULTRASPEC". The Astronomical Journal 148 (5): 100. doi:10.1088/0004-6256/148/5/100. 100. Bibcode: 2014AJ....148..100R. 
  14. ↑ "CCDM (Catalog of Components of Double & Multiple stars (Dommanget+ 2002)". VizieR. Centre de Données astronomiques de Strasbourg. http://vizier.u-strasbg.fr/viz-bin/VizieR-S?CCDM%20J08585%2b1151A. 
  15. ↑ "Acubens". Alcyone Bright Star Catalogue. http://www.alcyone.de/SIT/mainstars/SIT000505.htm#Cat4. 
  16. ↑ Allen, Richard Hinckley (1963). "Star Names — Their Lore and Meaning: Cancer". https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Cancer*.html. 
  17. ↑ "Naming Stars". International Astronomical Union. https://www.iau.org/public/themes/naming_stars/. 

Coordinates: Sky map 08h 58m 29.2217s, +11° 51′ 27.723″



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