7 Cancri

7 Cancri
Observation data; Epoch J2000 Equinox J2000
Constellation	Cancer
Right ascension	08h 03m 50.47704s[1]
Declination	+22° 04′ 14.9019″[1]
Apparent magnitude (V)	6.84[2]
Characteristics
Evolutionary stage	Giant star
Spectral type	gK3[2]
Astrometry
Radial velocity (Rv)	2.20[3] km/s
Proper motion (μ)	RA: −40.839[3] mas/yr ; Dec.: 5.213[3] mas/yr
Parallax (π)	5.8359 ± 0.0456[3] mas
Distance	559 ± 4 ly ; (171 ± 1 pc)
Absolute magnitude (MV)	+0.32[4]
Details
Radius	12[3] R☉
Luminosity	65[3] L☉
Temperature	4,757[3] K
Other designations
	BD+22°1845, HD 66347, HIP 39447, SAO 79903
Database references
SIMBAD	data

7 Cancri (7 Cnc) is a giant star in the constellation Cancer. Its apparent magnitude is 6.84 and it is about 559 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.[4] The more recent and more accurate Gaia Data Release 2 contains a parallax of 5.8359±0.0456 mas, resulting in a closer distance of 171±1 pc. Based on the Gaia distance, 7 Cancri has a bolometric luminosity 65 times that of the sun. Its temperature, based on its colour, is calculated to be 5,757 K and the resulting radius is 12 R_☉.[3]

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.[5]

References

Van Leeuwen, F. (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.
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.
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.
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. Vizier catalog entry
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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[hipparcos-1] Van Leeuwen, F. (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.

[eggen-2] 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.

[dr2-3] 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.

[xhip-4] 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. Vizier catalog entry

[bidelman-5] 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.