KRAZ (Beta Corvi). We learn in beginning astronomy that Johannes
Bayer listed the stars by Greek letters
according to their brightness within a constellation. Then we see
constellations like Corvus (the Crow)
and learn of the many exceptions. While bright third magnitude
(2.65) Kraz, Beta Corvi, is indeed number two as expected, for
reasons no one will know, Gienah (Gamma
Corvi) tops the list, the Alpha star (Alchiba) ranking a miserable
fourh-magnitude fifth. The proper name is no less mysterious. Assigned
in modern times, no one seems to know just what it means (though
one source claims "left-handed lynch pin"). Suggestions or sources
from readers are welcome: a contest (with no prizes save that we
will know). Physically, the star is a yellow-white class G (G5)
bright giant very much like (but more luminous than)
Mu Velorum, which
lies not terribly far away. From its distance of 140 light years,
this 5100 Kelvin star radiates with the power of 160 Suns, which together give a radius of 16 solar.
Though the star's (minimum) equatorial rotation speed is just over
double that of the Sun's, its large size means that it may take as
much as 180 days to make a full turn. The luminosity and
temperature also conspire to give us a calculated mass of 3.3
solar. Kraz is also seen to be a rather rare "star in transition,"
one with a quiet helium core that has nearly completed its
conversion into a fully-blown giant five times brighter than now,
after which the helium core will light up and fuse to carbon, which
will stabilize the star for a time at a somewhat dimmer luminosity.
Kraz appears to be all alone, with no observed companion. However
the star is also listed as a "weak" barium star. Such stars are
giants that were chemically contaminated by more-massive companions
that brought by-products of nuclear reactions to their surfaces,
passed them to their unevolved mates (the stars we now see), and
that have now shrunk to white dwarf status. Most likely the
classification is spurious, and Kraz really is by itself. Some 300
million years ago, Kraz (whatever it means) shone as a lovely blue-
white class B7 star. It will one day become a relatively massive,
though lonely, white dwarf itself, one that will never have the
chance to chemically enrich its own companion.