5 Cancri

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5 Cancri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cancer
Right ascension  08h 01m 30.28830s[1]
Declination +16° 27′ 19.1191″[1]
Apparent magnitude (V) 5.99[2]
Evolutionary stage main sequence[3]
Spectral type B9.5 Vn[4]
B−V color index −0.024±0.003[2]
Radial velocity (Rv)−10.0±1.5[5] km/s
Proper motion (μ) RA: +4.12[6] mas/yr
Dec.: −5.43[6] mas/yr
Parallax (π)6.2251 ± 0.1419[1] mas
Distance520 ± 10 ly
(161 ± 4 pc)
Absolute magnitude (MV)−0.09[2]
Mass2.93±0.10[3] M
Radius3.1[7] R
[3] L
Surface gravity (log g)4.5[4] cgs
[3] K
Rotational velocity (v sin i)188[3] km/s
Age36[4] Myr
Other designations
5 Cnc, BD+16°1612, HD 65873, HIP 39236, HR 3134, SAO 97485[8]
Database references

5 Cancri is a single[9] star in the zodiac constellation of Cancer, located around 520 light years away from the Sun. It is just visible to the naked eye under good seeing conditions as a dim, blue-white hued star with an apparent visual magnitude of 5.99.[2] This object is moving closer to the Sun with a heliocentric radial velocity of −10 km/s.[5]

At one point this was thought to be a spectroscopic binary system, it is a Be star with a weak circumstellar disk of gas that has around three times the radius of the host star.[10] The stellar classification of 5 Cancri is B9.5 Vn,[4] matching a B-type main-sequence star with "nebulous" lines due to rapid rotation. It is 36[4] million years old with a high projected rotational velocity of 188 km/s;[3] the star has 2.9[3] times the mass of the Sun and about 3.1[7] times the Sun's radius. It is radiating 121[3] times the Sun's luminosity from its photosphere at an effective temperature of 9,727 K.[3]


  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 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.
  3. ^ a b c d e f g h i Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691.
  4. ^ a b c d e 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.
  5. ^ a b Becker, Juliette C.; et al. (April 2015), "Extracting Radial Velocities of A- and B-type Stars from Echelle Spectrograph Calibration Spectra", The Astrophysical Journal Supplement Series, 217 (2): 13, arXiv:1503.03874, Bibcode:2015ApJS..217...29B, doi:10.1088/0067-0049/217/2/29, 29.
  6. ^ 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.
  7. ^ a b Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (Third ed.), 367: 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  8. ^ "5 Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-02-23.
  9. ^ 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.
  10. ^ Ghosh, K. K.; et al. (January 1999), "Observations of Bn and An stars: New Be stars", Astronomy and Astrophysics Supplement, 134: 359–364, Bibcode:1999A&AS..134..359G, doi:10.1051/aas:1999144.