At magnitude 4.07, Alpha Crateris is the second brightest star in Crater, the Cup (after Delta Crateris). Crater is among the dimmest of all classical constellations, and α Crt is the only star in it which has a proper name. "Alkes" comes from Arabic and means "the wine cup"; the name is also clearly related to the English word "alcohol."
Properties and Motion
Alkes is an orange class K1 III giant star with a 4725 K surface. At a distance of 175 light years, Alkes shines with 80 solar luminosities, giving the star a calculated radius 13 times the Sun's. With a mass estimated at around 2.5 solar masses, Alkes is clearly a "clump giant", i.e. one of a set of stars that all have about the same luminosity and temperature, and are all fusing helium to carbon and oxygen in their cores. Arcturus and Aldebaran are bright examples.
Unlike most helium-burning "clump giants," and unlike most stars around us, Alkes is also a high velocity star. Most of our neighbors are orbiting the Galaxy at a speed somewhat in excess of 200 km/sec. However, all the orbits are a bit different, so they drift relative to each other at speeds of 20 to 40 or so km/sec.
From its rate of angular motion across the sky (0.48" per year) and its radial velocity of 47 km/sec away form us, Alkes is moving relative to the Sun at 130 km/s, showing it to be a visitor from a different part of the Galaxy. The star has on occasion been placed into the group of "super-metal-rich" stars. It is clear that the star has come to us from the inner metal-rich part of the Galaxy, the galactic bulge. Alkes belongs to the odd category of "4150" stars, which seem to have a high abundance of the CN molecule, cyanogen.
[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]