DENEB KAITOS (Beta Ceti). Though the Beta star of the constellation Cetus, the "Whale" or "Sea Monster," Deneb Kaitos is -- at mid-second-magnitude -- (2.04) -- notably the brightest of a fairly hard-to-find figure. The Arabic name simply means the "whale's tail," though that is taken from a longer phrase that describes the star's position a bit more precisely in the southern branch of the tail. A lesser name for the star is "Diphda," also from Arabic and referring to a "first frog," where Fomalhaut was the "second frog." The star is remarkably easy to find, standing out in an otherwise lonely area south of the Great Square of Pegasus and northeast of Fomalhaut. Like so many other naked eye stars, Deneb Kaitos is a dying class K (K0) giant, but like Arcturus is a bit warmer than most. Falling near the border of classes G and K, it has a temperature of 4800 Kelvin. From its distance of only 96 light years (which accounts for its relative brightness), we find a luminosity (accounting for a little infrared radiation) 145 times that of the Sun, which combined with the temperature gives us a radius 17 times solar, large as befits a giant, but certainly not all THAT large. Its mass is estimated to be about three times that of the Sun. Deneb Kaitos is a remarkable enigma. It is one of the brightest X-ray stars in the solar neighborhood, the high-energy radiation coming from a magnetically heated corona of a few million Kelvin rather like that belonging to the Sun. The magnetism is expected to be related to rotation, yet the star is rotating rather slowly. Such high X-ray activity also suggests that it has only recently begun to expire and still has characteristics from its solar-like "main sequence" phase when it appeared something like Vega and Altair and was fusing hydrogen into helium. It would therefore have a contracting helium core. Its detailed chemical composition, however, suggests that it has been around long enough for its internal helium to begin to fuse to carbon. If nothing else, Deneb Kaitos shows us that even the nearby stars are not all that well understood.
Written by Jim Kaler. Return to STARS.