Beta Corvi - Kraz

At magnitude 2.65, the star Kraz, or Beta Corvi, is second-brightest in the constellation Corvus. Its proper name was assigned in modern times, but no one seems to know just what it means (though one source claims "left-handed lynch pin").

Properties

Physically, the star is a yellow-white class G5 II bright giant very much like μ Vel, which lies not far away. From its distance of 140 light years, this 5100 K star radiates 160 solar luminosities, which give it a radius 16 times solar. Though the star's minimum equatorial rotation speed is just over double the Sun's, its large size means that it may take as much as 180 days to make a full turn. Its luminosity and temperature also imply a calculated mass of 3.3 suns.

Evolution

Kraz is a rather rare star in transition, with a quiet helium core that has nearly completed its conversion into a fully-blown giant. When this process completes, Kraz will be five times brighter than it is now; then the helium core will light up and fuse to carbon, which will stabilize the star for a time at a somewhat dimmer luminosity. Some 300 million years ago, Kraz shone as a blue-white class B7 star. It will one day become a relatively massive white dwarf.

Kraz appears to be alone, with no observed companion. However, it is also listed as a weak barium star. Such stars are giants that were chemically contaminated by more-massive companions that passed the by-products of their nuclear reactions to their mates, and have now evolved to white dwarf status. Most likely the classification is spurious, and Kraz really is single.

[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]