45 Cancri

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45 Cancri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cancer
Right ascension  08h 43m 12.32940s[1]
Declination +12° 40′ 51.1486″[1]
Apparent magnitude (V) 5.62[2]
Spectral type A3 III: + G7 III[3]
B−V color index 0.435±0.005[2]
Radial velocity (Rv)−6.2±2.3[2] km/s
Proper motion (μ) RA: −9.828[1] mas/yr
Dec.: +0.916[1] mas/yr
Parallax (π)4.7700 ± 0.1025[1] mas
Distance680 ± 10 ly
(210 ± 5 pc)
Absolute magnitude (MV)−1.62[2]
Period (P)1009.36±0.12 d
Eccentricity (e)0.461±0.002
Semi-amplitude (K1)
20.04±0.06 km/s
Semi-amplitude (K2)
20.75±0.02 km/s
Luminosity377.09[2] L
Surface gravity (log g)2.72[5] cgs
Temperature5,058[5] K
Metallicity [Fe/H]−0.69±0.22[5] dex
Rotational velocity (v sin i)5.3[6] km/s
Other designations
A1 Cancri,[7], 45 Cnc, BD+13°1972, FK5 2686, HD 74228, HIP 42795, HR 3450, SAO 98069[8]
Database references

45 Cancri is a binary star[4] system in the zodiac constellation of Cancer, located 680 light years away from the Sun.[1] It has the Bayer designation A1 Cancri,[7] (A1 Cnc); 45 Cancri is the Flamsteed designation. It is visible to the naked eye as a faint, white-hued star at an apparent visual magnitude of 5.62.[2] The pair form a double-lined spectroscopic binary with an orbital period of 2.76 years and an eccentricity of 0.46.[4]


  1. ^ a b c d e f 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 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. ^ Ginestet, N.; Carquillat, J. M. (2002), "Spectral Classification of the Hot Components of a Large Sample of Stars with Composite Spectra, and Implication for the Absolute Magnitudes of the Cool Supergiant Components", The Astrophysical Journal Supplement Series, 143 (2): 513, Bibcode:2002ApJS..143..513G, doi:10.1086/342942
  4. ^ a b c Eggleton, Peter P.; Yakut, Kadri (July 2017), "Models for 60 double-lined binaries containing giants", Monthly Notices of the Royal Astronomical Society, 468 (3): 3533–3556, arXiv:1611.05041, Bibcode:2017MNRAS.468.3533E, doi:10.1093/mnras/stx598.
  5. ^ a b c Soubiran, Caroline; et al. (2016), "The PASTEL catalogue: 2016 version", Astronomy & Astrophysics, 591: A118, arXiv:1605.07384, Bibcode:2016A&A...591A.118S, doi:10.1051/0004-6361/201628497.
  6. ^ Schröder, C.; et al. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" (PDF), Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377
  7. ^ a b HD 74228, HD-DM-GC-HR-HIP-Bayer-Flamsteed Cross Index, N. D. Kostjuk, Institute of Astronomy of Russian Academy of Sciences, 2002; CDS ID IV/27A.
  8. ^ "45 Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-03-04.