66 Cancri

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66 Cancri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cancer
Right ascension  09h 01m 24.13000s[1]
Declination +32° 15′ 08.2666″[1]
Apparent magnitude (V) 5.870[2] (5.95 + 8.56)[3]
Evolutionary stage main sequence[4]
Spectral type A2 V[2]
B−V color index 0.088±0.007[5]
Radial velocity (Rv)−12.8±2.9[6] km/s
Proper motion (μ) RA: +0.48[7] mas/yr
Dec.: +0.34[7] mas/yr
Parallax (π)6.8850 ± 0.1020[1] mas
Distance474 ± 7 ly
(145 ± 2 pc)
Absolute magnitude (MV)0.14[5]
Mass2.73±0.11[4] M
[4] L
Surface gravity (log g)4.0[2][4] cgs
[4] K
Rotational velocity (v sin i)183[4] km/s
Age162[2] Gyr
Other designations
66 Cnc, BD+32°1829, HD 77104, HIP 44307, HR 3587, SAO 61202, WDS 09014+3215[8]
Database references

66 Cancri is a binary star[9] system near the northern border of the zodiac constellation of Cancer, located 474 light years away from the Sun. It is visible to the naked eye as a faint, white-hued star with a combined apparent visual magnitude of 5.87.[2] The pair are moving closer to the Earth with a heliocentric radial velocity of −13 light years.[6] As of 2003, the magnitude 8.56 companion was located at an angular separation of 4.43 along a position angle of 134° from the primary.[9]

The brighter member of the system, designated component A, is an A-type main-sequence star with a stellar classification of A2 V.[2] It is around 162[2] million years old with a high rate of spin, showing a projected rotational velocity of 183 km/s.[4] Estimates of the mass of the star range from 1.7[10] up to 2.73[4] times the mass of the Sun. It is radiating 96[4] times the Sun's luminosity from its photosphere at an effective temperature of 8,974 K.[4]


  1. ^ 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.
  2. ^ a b c d e f g Gullikson, Kevin; Kraus, Adam; Dodson-Robinson, Sarah (2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal, 152 (2): 40, Bibcode:2016AJ....152...40G.
  3. ^ Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
  4. ^ a b c d e f g h i j Zorec, J.; Royer, F.; Asplund, Martin; Cassisi, Santi; Ramirez, Ivan; Melendez, Jorge; Bensby, Thomas; Feltzing, Sofia (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy and Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/20111769.
  5. ^ a b 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 de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  7. ^ a b van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  8. ^ "66 Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-03-09.
  9. ^ a b Roberts, Lewis C., Jr.; et al. (November 2005), "Adaptive Optics Photometry and Astrometry of Binary Stars", The Astronomical Journal, 130 (5): 2262–2271, Bibcode:2005AJ....130.2262R, doi:10.1086/491586.
  10. ^ Gullikson, Kevin; et al. (August 2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal, 152 (2): 13, arXiv:1604.06456, Bibcode:2016AJ....152...40G, doi:10.3847/0004-6256/152/2/40, 40.