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[15]) and Ab. HD 73711 is also suspected of being a spectroscopic binary.[16]
Nomenclature
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.[17] In his Uranometria, Bayer cited (among others) the name Melleff or Meeleph for the cluster, from Arabic Al Ma'laf, the Stall;[18] as Meleph, this name is also now applied specifically to this star.[19]
In 2016, the IAU organized a Working Group on Star Names (WGSN)[20] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[21] 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]
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 A5III,[5] which matches an A-typegiant star. The spectrum displays the chemically peculiar characteristics of an Am star.[22] 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 637million years.[11]
HD 73711 is another Am star, given a stellar classification of F0III 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 and so is till on the main sequence.[3]
Notes
↑Calculated using distance of 183.1 parsecs and estimated angular diameter of 0.000194 arcseconds (0.194mas). 183.1•0.000194•107.5 = 3.8R☉
↑Calculated using distance of 183.1 parsecs and estimated angular diameter of 0.000136 arcseconds (0.136mas). 183.1•0.000136•107.5 = 2.7R☉
12Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42 (2): 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
12Glebocki, R.; Gnacinski, P. (2005). "VizieR Online Data Catalog: Catalog of Stellar Rotational Velocities (Glebocki+ 2005)". VizieR On-line Data Catalog: III/244. Originally Published in: 2005csss...13..571G; 2005yCat.3244....0G. 3244. Bibcode:2005yCat.3244....0G.
↑Wang, J. J.; etal. (1995). "High-precision study of proper motions and membership of 924 stars in the central region of Praesepe". Astronomy and Astrophysics Supplement. 113: 419. Bibcode:1995A&AS..113..419W.
