55 Cancri

For other stars with this Bayer designation, see ρ Cancri.

55 Cancri
Location of 55 Cancri (circled in red)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cancer
Pronunciation /ˈkæŋkraɪ/ or /ˈkæŋkriː/
55 Cancri A
Right ascension 08h 52m 35.8111s[1]
Declination +28° 19′ 50.955″[1]
Apparent magnitude (V) 5.95[2]
55 Cancri B
Right ascension 08h 52m 40.8627s[3]
Declination +28° 19′ 58.821″[3]
Apparent magnitude (V) 13.15[4]
Characteristics
55 Cancri A
Evolutionary stage Between main sequence and subgiant
Spectral type K0IV–V[5]
U−B color index 0.63[6]
B−V color index 0.87[6]
55 Cancri B
Evolutionary stage Main sequence (red dwarf)
Spectral type M4.5V[7]
B−V color index 1.7[4]
Astrometry
55 Cancri A
Radial velocity (Rv)27.51[1] km/s
Proper motion (μ) RA: −485.681±0.040[1] mas/yr
Dec.: −233.517±0.037[1] mas/yr
Parallax (π)79.4482 ± 0.0429 mas[1]
Distance41.05 ± 0.02 ly
(12.587 ± 0.007 pc)
Absolute magnitude (MV)+5.50[8]
55 Cancri B
Proper motion (μ) RA: −481.176±0.041[3] mas/yr
Dec.: −244.544±0.032[3] mas/yr
Parallax (π)79.6560 ± 0.0475 mas[3]
Distance40.95 ± 0.02 ly
(12.554 ± 0.007 pc)
Absolute magnitude (MV)+12.58±0.088[9]
Details
55 Cnc A
Mass0.905±0.015[10] M☉
Radius0.943±0.010[10] R☉
Luminosity0.582±0.014[10] L☉
Surface gravity (log g)4.45±0.01[10] cgs
Temperature5,172±18[11] K
Metallicity [Fe/H]0.35±0.10[11] dex
Rotation38.8±0.05 days[11]
Rotational velocity (v sin i)<1.23±0.01[11] km/s
Age8.6±1[11] Gyr
55 Cnc B
Mass0.264±0.007[12] M☉
Radius0.268±0.009[12] R☉
Luminosity0.00788±0.00013[12] L☉
Temperature3,320±51[12] K
Metallicity [Fe/H]0.15±0.16[12] dex
Rotation6.11+3.2
−1.9 days[9]
Rotational velocity (v sin i)2.36[9] km/s
Other designations
Copernicus, Rho1 Cancri, 55 Cnc, BD+28°1660, GJ 324, HD 75732, HIP 43587, HR 3522, SAO 80585
Database references
SIMBADdata
55 Cnc B
Exoplanet Archivedata
ARICNSdata

55 Cancri is a binary star system located 41[1] light-years away from the Sun in the zodiac constellation of Cancer. It has the Bayer designation Rho1 Cancri (ρ1 Cancri); 55 Cancri is the Flamsteed designation (abbreviated 55 Cnc). The system consists of a K-type star (designated 55 Cancri A, also named Copernicus /koʊˈpɜːrnɪkəs/)[13] and a smaller red dwarf (55 Cancri B).

As of 2015, five extrasolar planets (designated 55 Cancri b, c, d, e and f; named Galileo, Brahe, Lipperhey, Janssen and Harriot, respectively) are known to orbit 55 Cancri A.

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  9. ^ a b c Cite error: The named reference houdebine was invoked but never defined (see the help page).
  10. ^ a b c d Cite error: The named reference vonbraun2011 was invoked but never defined (see the help page).
  11. ^ a b c d e Cite error: The named reference Bourrier2018 was invoked but never defined (see the help page).
  12. ^ a b c d e Cite error: The named reference Carmenes2019 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference IAU-CSN was invoked but never defined (see the help page).