7 Cancri
Observation data
Epoch J2000      Equinox J2000
Constellation Cancer
Right ascension 08h 03m 50.47881s[1]
Declination +22° 04′ 14.8926″[1]
Apparent magnitude (V) 6.84[2]
Characteristics
Evolutionary stage red giant branch[1]
Spectral type gK3[2]
Astrometry
Radial velocity (Rv)1.90[1] km/s
Proper motion (μ) RA: −40.866[1] mas/yr
Dec.: −5.129[1] mas/yr
Parallax (π)5.8616 ± 0.0215 mas[1]
Distance556 ± 2 ly
(170.6 ± 0.6 pc)
Absolute magnitude (MV)+0.32[3]
Details
Mass3.2[1] M☉
Radius13[1] R☉
Luminosity75[1] L☉
Surface gravity (log g)2.5[1] cgs
Temperature4,711[1] K
Metallicity [Fe/H]+0.02 dex
Age318 Myr
Other designations
BD+22°1845, HD 66347, HIP 39447, SAO 79903
Database references
SIMBADdata

7 Cancri (7 Cnc) is a giant star in the constellation Cancer. Its apparent magnitude is 6.84 and it is about 556 ly away.

The annual parallax of 7 Cancri determined from the Hipparcos satellite mission is 488±0.56 mas, giving a distance of 202 pc with an 11.5% margin of error.[3] The more recent and more accurate Gaia Data Release 3 contains a parallax of 5.8616±0.0215 mas, resulting in a closer distance of 171±1 pc. Based on the Gaia distance, 7 Cancri has a bolometric luminosity 75 times that of the sun. Its temperature, based on its colour, is calculated to be 4,711 K and the resulting radius is 13 R☉.[1]

7 Cancri is a cool giant star. It has evolved away from the main sequence after exhausting its core hydrogen and expanded so that it is larger and more luminous than the sun, although cooler. It is one of 220 Flamsteed stars that are too faint to have been included in the Bright Star Catalogue.[4]

References

  1. ^ a b c d e f g h i j k l m Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b Eggen, O. J. (1986). "Hyades and Sirius supercluster members brighter than magnitude (V) 7.1. II - Right ascension six to twelve hours". Astronomical Society of the Pacific. 98: 423. Bibcode:1986PASP...98..423E. doi:10.1086/131772.
  3. ^ 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. S2CID 119257644. Vizier catalog entry
  4. ^ Bidelman, W. P. (1990). "Flamsteed stars not contained in the Yale "Catalogue of Bright Stars"". Bulletin d'Information du Centre de Données Stellaires. 38: 13. Bibcode:1990BICDS..38...13B.
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