Alpha Crateris (α Crateris, abbreviated Alpha Crt, α Crt), officially named Alkes/ˈælkɛs/,[8][9] is a star in the constellationofCrater. It is a cool giant star about 43.2 parsecs (141 ly) away.
It bore the traditional name Alkes, from the Arabic الكاس alkās or الكأس alka's "the cup". In the catalogue of stars in the CalendariumofAl Achsasi al Mouakket, this star was designated Aoul al Batjna (أول ألباطیة awwal al-bāṭiya), which was translated into LatinasPrima Crateris, meaning "first [star] of the Cup".[10] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[11] to catalogue and standardize proper names for stars. The WGSN approved the name Alkes for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.[9]
Alpha Crateris is an orange giant of spectral type K1III. It has an apparent magnitude of 4.07, and is 174 light-years from Earth. It is thought to be a horizontal branch star, meaning it is fusing helium in its core after a helium flash. Cool horizontal branch stars are often called red clump giants as they form a noticeable grouping near the hot edge of the red giant branch in the H–R diagrams of clusters with near-solar metallicity. On this basis it is calculated to have a mass of 1.81 M☉, a luminosity of 66 L☉, and an age around two billion years. Its surface temperature is 4691 K. Or it might be a red-giant branch star, still fusing hydrogen in a shell around an insert helium core, in which case it would be slightly less massive, older, cooler, larger, and more luminous.[7]
^Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
^Houk, N.; Smith-Moore, M. (1988). "Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Declinations -26°.0 to -12°.0". Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4. Bibcode:1988mcts.book.....H.
10h59m46.4647s, −18° 17′ 55.62″
