WAZN (Beta Columbae). Though the second
brightest star in Columba (the Dove),
third magnitude (3.12) Beta Columbae takes third place in
recognition after brighter third magnitude Phact (Alpha Col, 2.64) and the runaway star
Mu Col. Otherwise an ordinary class K
(K2) giant, it has three oddities that bring it to the table. The
first is confusion over the name, which derives from the Arabic
"al-wazn," meaning "the weight," the weight of WHAT not at all
clear. Kunitzsch and Smart say that the term seems to apply to
"one of a pair of stars." Which one is not clear either. The name
has been related both to Alpha
Centauri and to Delta Canis Majoris,
and then also wound up with our Beta Columbae. The latter two
stars are distinguished by spelling, Delta CMa known as Wezen, Beta
Col as Wazn. At a distance of 86 light years, this calm, core-
helium-fusing giant shines
with the light of 53 Suns from its 4535
Kelvin surface, which leads to a smallish (for a giant) radius of
12 solar, a mass of about 1.7 solar, and an age of about two
billion years. The rotation velocity is unknown, there is no X-ray
emission, and there are no known companions. As the second of the
oddities, what it does have is speed. Moving at a rather amazing
103 kilometers per second relative to the Sun (6 to 7 times
normal), it is going almost as fast as runaway Mu Col, in this case
showing it to be a visitor from another part of the Galaxy. Most such speedsters are
passing through the Galaxy's disk from the extended halo and have
the halo's low metal abundance. Enter the third oddity. Instead
of a low metal content, Wazn's metal-to-hydrogen ratio is some 30
percent HIGHER than the Sun's. Nevertheless, for all the
strangeness, Wazn, which started life as a relatively modest class
A dwarf, will (like any other giant) before long lose its outer
hydrogen envelope through a strong wind that will develop after the
helium fuel is gone, and then expire as a relatively ordinary white dwarf -- though one
with a lot of zip in it.
Written by Jim Kaler 3/09/07. Return to STARS.