Epsilon Cancri (ε Cancri, abbreviated Epsilon Cnc, ε Cnc) is a white-hued binary star system in the zodiac constellation of Cancer. It is the brightest member of the Beehive Cluster^[14] with an apparent visual magnitude of +6.29,^[2] which is near the lower limit of visibility with the naked eye. The annual parallax shift of 5.4 mas as seen from Earth yields a distance estimate of approximately 606 light-years from the Sun.

Quick Facts Observation data Epoch J2000 Equinox J2000, Apparent magnitude (V) ...

ε Cancri

Location of ε Cancri (circled red)
Observation data Epoch J2000      Equinox J2000
Constellation	Cancer
ε Cnc A
Right ascension	08h 40m 27.01010s[1]
Declination	19° 32′ 41.3243″[1]
Apparent magnitude (V)	6.29[2]
HD 73711
Right ascension	08h 40m 18.09670s[3]
Declination	19° 31′ 55.1636″[3]
Apparent magnitude (V)	7.535[4]
Characteristics
ε Cnc A
Spectral type	A5 III[5] (kA3hA5mF0)[6]
U−B color index	+0.16[7]
B−V color index	+0.17[7]
HD 73711
Spectral type	F0III[8] (kA3hA5mF0)[9]
Astrometry
ε Cnc A
Radial velocity (Rv)	+29.9±1.1[10] km/s
Proper motion (μ)	RA: −36.293[1] mas/yr Dec.: −12.133[1] mas/yr
Parallax (π)	5.3836 ± 0.0474 mas[1]
Distance	606 ± 5 ly (186 ± 2 pc)
Absolute magnitude (MV)	+0.00[2]
HD 73711
Proper motion (μ)	RA: −36.251[3] mas/yr Dec.: −12.118[3] mas/yr
Parallax (π)	5.4103 ± 0.0308 mas[3]
Distance	603 ± 3 ly (185 ± 1 pc)
Orbit[11]
Primary	ε Cnc Aa
Companion	ε Cnc Ab
Period (P)	35.14101±0.00005 d
Semi-major axis (a)	1.9127±0.0004 mas
Eccentricity (e)	0.4195±0.0003
Inclination (i)	81.454±0.010°
Longitude of the node (Ω)	356.069±0.014°
Periastron epoch (T)	2448314.598 ± 0.016
Argument of periastron (ω) (primary)	258.38±0.02°
Semi-amplitude (K1) (primary)	56.60±0.03 km/s
Semi-amplitude (K2) (secondary)	61.55±0.10 km/s
Details
ε Cnc Aa
Mass	2.420[11] M☉
Radius	4.8[4] R☉
Luminosity	90[4] L☉
Surface gravity (log g)	3.49[12] cgs
Temperature	8,163[4] K
Metallicity [Fe/H]	+0.10[12] dex
Rotational velocity (v sin i)	49.2[13] km/s
Age	637 ± 19[11] Myr
ε Cnc Ab
Mass	2.226[11] M☉
HD 73711
Mass	2.54[3] M☉
Radius	2.4[3] R☉
Luminosity	43.5[3] L☉
Surface gravity (log g)	4.09[3] cgs
Temperature	9,572[3] K
Metallicity [Fe/H]	+0.79[3] dex
Rotational velocity (v sin i)	56.3[8] km/s
Age	407[3] Myr
Other designations
CCDM J08404+1932, WDS J08405+1933
ε Cancri: Meleph, ε Cnc, 41 Cancri, BD+20°2171, GC 11904, HD 73731, HIP 42556, HR 3429, SAO 98024, GSC 01395-02733
HD 73711: BD+20°2163, GC 11893, HD 73711, SAO 98018
Database references
SIMBAD	ε Cancri
	HD 73711

Close

The binary pair has the designation WDS J08405+1933. The primary star is designated Epsilon Cancri and the secondary is HD 73711. Epsilon Cancri is itself a spectroscopic binary with components designated Aa (also named Meleph^[15]) and Ab. HD 73711 is also suspected of being a spectroscopic binary.^[16]

ε Cancri (Latinised to Epsilon Cancri) is the system's Bayer designation, which originally referred to the entire cluster.^[17]

In 2016, the IAU organized a Working Group on Star Names (WGSN)^[18] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.^[19] It approved the name Meleph for the component Epsilon Cancri Aa on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.^[15]

The system is moving away from the Sun with a radial velocity of +30 km/s.^[10]

Epsilon Cancri A is a double-lined spectroscopic binary system with an orbital period of 35.14 days and eccentricity of 0.42.^[11] It has a stellar classification of A5 III,^[5] which matches an A-type giant star. The spectrum displays the chemically peculiar characteristics of an Am star.^[20] Its spectral type has been listed as kA3hA5mF0, indicating the different spectral types shown by spectral lines of calcium, hydrogen, and other metals.^[6] Despite the spectral classification, evolutionary models suggest that the star is still on the main sequence, although at the very end of its hydrogen-burning life.^[1] The age of the system is estimated to be around 637 million years.^[11]

HD 73711 is another Am star, given a stellar classification of F0 III on the basis of its hydrogen absorption lines but a more complete classification of kA3hA5mF0. Although the spectral class would indicate that the star is a giant, models suggest that it is still fusing hydrogen in its core.^[3]