Epsilon Cancri

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Template:Short description

ε Cancri
Template:Location mark
Location of ε Cancri (circled red)
Observation data
Epoch J2000      Equinox J2000
Constellation Cancer
ε Cnc A
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 6.29[2]
HD 73711
Right ascension Template:RA[3]
Declination Template:DEC[3]
Apparent magnitude (V) 7.535[4]
Characteristics
ε Cnc A
Spectral type A5 III[5] (kA3hA5mF0)[6]
U−B Template:Engvar +0.16[7]
B−V Template:Engvar +0.17[7]
HD 73711
Spectral type F0III[8] (kA3hA5mF0)[9]
Astrometry
ε Cnc A
Radial velocity (Rv)Template:Val[10] km/s
Proper motion (μ) RA: −36.293 mas/yr[1]
Dec.: −12.133 mas/yr[1]
Parallax (π)5.3836±0.0474 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)+0.00[2]
HD 73711
Proper motion (μ) RA: −36.251 mas/yr[3]
Dec.: −12.118 mas/yr[3]
Parallax (π)5.4103±0.0308 mas[3]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Orbit[11]
Primaryε Cnc Aa
Companionε Cnc Ab
Period (P)Template:Val
Semi-major axis (a)Template:Val
Eccentricity (e)Template:Val
Inclination (i)Template:Val°
Longitude of the node (Ω)Template:Val°
Periastron epoch (T)Template:Val
Argument of periastron (ω)
(primary)
Template:Val°
Semi-amplitude (K1)
(primary)
Template:Val km/s
Semi-amplitude (K2)
(secondary)
Template:Val km/s
Details[11]
ε Cnc Aa
MassTemplate:Val Template:Solar mass
Radius~Template:Solar radius calculatorTemplate:Efn Template:Solar radius
Luminosity~59.8 Template:Solar luminosity
Surface gravity (log g)~3.6 cgs
Temperature~8,060 K
Metallicity [Fe/H]~ +0.2 dex
AgeTemplate:Val Myr
ε Cnc Ab
MassTemplate:Val Template:Solar mass
Radius~Template:Solar radius calculatorTemplate:Efn Template:Solar radius
Surface gravity (log g)~4.0 cgs
Temperature~8,330 K
Metallicity [Fe/H]~ +0.2 dex
AgeTemplate:Val Myr
HD 73711
Mass2.54[3] Template:Solar mass
Radius2.4[3] Template:Solar radius
Luminosity43.5[3] Template:Solar luminosity
Surface gravity (log g)4.09[3] cgs
Temperature9,572[3] K
Metallicity [Fe/H]+0.79[3] dex
Rotational velocity (v sin i)56.3[8] km/s
Age407[3] Myr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist
ε Cancri: Template:Odlist
HD 73711: Template:Odlist
Database references
SIMBADε Cancri
HD 73711

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Epsilon Cancri is a white-hued multiple star system in the zodiac constellation of Cancer. Its name is a Bayer designation that is Latinized from ε Cancri, and abbreviated Epsilon Cnc or ε Cnc. This is the brightest member of the Beehive Cluster (or Praesepe)[12] 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 Template:Val as seen from Earth yields a distance estimate of approximately Template:Convert from the Sun. The system is moving away from the Sun with a radial velocity of +30 km/s.[10]

The outer 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[13]) and Ab. HD 73711 is also suspected of being a spectroscopic binary.[14]

Nomenclature

File:M44 Heggie.jpg
Praesepe. ε Cancri is the brightest blue star, near the centre of the image.

ε Cancri (Latinised to Epsilon Cancri) is the system's Bayer designation, which originally referred to the entire Beehive Cluster.[15] In his Uranometria, Bayer cited (among others) the name Melleff or Meeleph for the cluster, from Arabic Al Ma'laf, the Stall;[16] as Meleph, this name is also now applied specifically to this star.[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.[13]

Properties

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]

Notes

Template:Notelist

References

Template:Reflist

Template:Stars of Cancer

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