45 Cancri

This article is about A1 Cancri. For other stars with this Bayer designation, see A Cancri.
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]
Characteristics
Spectral type G8 III and A3 III[3]
B−V color index 0.435±0.005[2]
Astrometry
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 mas[1]
Distance680 ± 10 ly
(210 ± 5 pc)
Absolute magnitude (MV)−1.62[2]
Orbit[4]
Period (P)1,009.36±0.12 d
Eccentricity (e)0.461±0.002
Semi-amplitude (K1)
(primary)		20.04±0.06 km/s
Semi-amplitude (K2)
(secondary)		20.75±0.02 km/s
Details
45 Cnc A
Mass3.11±0.10[3] M☉
Radius13.86+5.03
−1.73[1] R☉
Luminosity210.3±5.4[1] 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
45 Cnc B
Mass3.00±0.10[3] M☉
Luminosity190.5+43.9
−35.6[3] L☉
Other designations
A1 Cnc,[7], 45 Cnc, BD+13°1972, FK5 2686, HD 74228, HIP 42795, HR 3450, SAO 98069[8]
Database references
SIMBADdata

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] 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] They are drifting closer to the Earth with a heliocentric radial velocity of −6 km/s.[2]

The primary, designated component A, is an aging giant star with a stellar classification of G8 III,[9] but has most likely not yet made multiple ascents up the red giant branch.[3] It has 3.11[3] times the mass of the Sun and has expanded to 14[1] times the Sun's radius. The star is radiating 210[1] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 5,058 K.[5] The less evolved secondary, component B is likewise a giant star, having a class of A3 III. It has three times the mass of the Sun and shines with 191 times the Sun's luminosity.[3]

  1. ^ a b c d e f g h i j Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b c d e f g Cite error: The named reference Griffin2015 was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference Eggleton2017 was invoked but never defined (see the help page).
  5. ^ a b c d Cite error: The named reference Soubiran2016 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Schröder2009 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference crossindex was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference ginestat2002 was invoked but never defined (see the help page).