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Kappa Cancri
	Location of κ Cancri (circled)
	; A light curve for Kappa Cancri, plotted from TESS data
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Cancer
Right ascension	09h 07m 44.80955s
Declination	+10° 40′ 05.5196″
Apparent magnitude (V)	+5.233
Characteristics
Spectral type	B8 IIIp
B−V color index	−0.113
Variable type	α2 CVn
Astrometry
Proper motion (μ)	RA: −18.31 mas/yr ; Dec.: −12.105 mas/yr
Parallax (π)	5.3209 ± 0.1298 mas
Distance	610 ± 10 ly ; (188 ± 5 pc)
Absolute magnitude (MV)	−0.82
Orbit
Period (P)	6.3933 d
Eccentricity (e)	0.13
Periastron epoch (T)	2440001.95 JD
Argument of periastron (ω); (secondary)	157°
Semi-amplitude (K1); (primary)	67.4 km/s
Details
κ Cnc A
Mass	4.5 M☉
Radius	5.0 R☉
Luminosity	322 L☉
Surface gravity (log g)	3.7±0.1 cgs
Temperature	12,800±200 K
Metallicity [Fe/H]	+0.51 dex
Rotational velocity (v sin i)	6±2 km/s
κ Cnc B
Mass	2.1 M☉
Radius	2.4 R☉
Surface gravity (log g)	4.0 cgs
Temperature	8,500 K
Rotational velocity (v sin i)	40 km/s
Other designations
	κ Cnc, 76 Cancri, BD+11°1984, FK5 1238, HD 78316, HIP 44798, HR 3623, SAO 98378
Database references
SIMBAD	data

Kappa Cancri, Latinized from κ Cancri, is a blue-white hued binary star system in the zodiac constellation of Cancer. It is faintly visible to the naked eye with an apparent visual magnitude of +5.23.^[3] The magnitude difference between the two stars is about 2.6.^[10] Based upon an annual parallax shift of 5.3209 mas as seen from the Earth,^[2] the system is located roughly 610 light-years from the Sun.

This is a single-lined spectroscopic binary^[3] star system with an orbital period of 6.39 days and an eccentricity of 0.13.^[7] The primary, component A, has a stellar classification of B8 IIIp,^[4] suggesting it is a B-type giant star. It a mercury-manganese star, a type of chemically peculiar star showing large overabundances of those two elements in the outer atmosphere.^[3] It is classified as an Alpha2 Canum Venaticorum type variable star and its brightness varies from magnitude +5.22 to +5.27 with a period of five days.^[5]

The primary component has 4.5 times the mass of the Sun, five times the Sun's radius, and an effective temperature of 13,200 K. The secondary, component B, is a smaller star with 2.1 times the mass and 2.4 times the radius of the Sun, having an effective temperature of 8,500 K.^[8]

References

^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 5 December 2022.
^ ^a ^b ^c ^d ^e ^f Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
^ ^a ^b ^c ^d ^e ^f ^g ^h Maza, Natalia L.; et al. (December 2014), "A non-LTE spectral analysis of the ³He and ⁴He isotopes in the HgMn star κ Cancri", Astronomy & Astrophysics, 572: 7, arXiv:1412.2052, Bibcode:2014A&A...572A.112M, doi:10.1051/0004-6361/201425037, S2CID 119116996, A112.
^ ^a ^b Levato, H. (1975), "Rotational velocities and spectral types for a sample of binary systems", Astronomy and Astrophysics, 19: 91, Bibcode:1975A&AS...19...91L.
^ ^a ^b Samus', N. N.; et al. (January 2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
^ ^a ^b ^c 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.
^ ^a ^b Pourbaix, D.; et al. (2004), "S_B⁹: The ninth catalogue of spectroscopic binary orbits", Astronomy & Astrophysics, 424 (2): 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088.
^ ^a ^b Ryabchikova, T. (April 1998), "Abundance analysis of SB2 binary stars with HgMn primaries", Contributions of the Astronomical Observatory Skalnate Pleso, 27 (3): 319–323, arXiv:astro-ph/9805063, Bibcode:1998CoSka..27..319R.
^ "kap Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-19.
^ Ryabchikova, T.; et al. (April 1998), "Discovery of the secondary star of the HgMn binary kappa CANCRI", Contributions of the Astronomical Observatory Skalnate Pleso, 27 (3): 258–260, arXiv:astro-ph/9805143, Bibcode:1998CoSka..27..258R.