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CIH

High overhead in northern autumn evenings lies the W- shaped constellation Cassiopeia, in mythology the Queen and mother to Andromeda, to us brilliant against the background of the Milky Way and fully circumpolar from most of the United States and all of Canada. At the center of the "W" lies our star. It stands out in that, oddly, it is among the brightest stars in the sky that carries no proper "western" name, though known as Tsih (the whip) in old China. We do not know why at mid-second magnitude the ancients paid it so little attention. The four eastern stars of the "W" are all about the same brightness and were together known through Arabic as "the stained hand." The shortened version of the term, "Caph," eventually went to the eastern-most (the Beta) star, so perhaps Gamma (usually denoting third brightest in a constellation) is a victim of early collectivization. At a distance of 600 light years, this blue star radiates with a huge luminosity some 70,000 times that of the Sun, after accounting for invisible ultraviolet radiation from the 25,000 Kelvin (hot class B) surface and a small bit of absorption by the dust of interstellar space that makes the star appear a bit fainter than it would were space clear. Cih is more, however, than just another luminous star, even more than one that is apparently approaching the end of its hydrogen-fusing life. First, it is also unpredictably variable. In 1937, the star brightened almost to first magnitude, and it has been as faint as third. Perhaps its lack of a proper name tells us of ancient faintness. Then, in 1866 the father of the study of stellar spectra, Father Angelo Secchi, discovered that the star radiated light in specific colors associated with hydrogen. Cih thus has the distinction of being the first known "Be star," the "e" standing for "emission." Be stars are fairly common and weird. All rotate with enormous speed, Cih spinning at least 300 kilometers per second at its equator, 150 times the solar rate. The rotation and high luminosity conspire to drive mass from the star into a surrounding disk that radiates the "emissions," mass loss apparently related to the brightness variations. Gamma Cas also radiates X-rays, though no one is quite sure why, theories including the transfer of lost mass to a compact companion and magnetic effects similar to those found on the Sun. If any star deserves a name, surely this one does. (Thanks to Monica Shaw, who helped research this star).