Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/5/84; site mordor.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!decvax!genrad!panda!talcott!harvard!seismo!ut-sally!mordor!space@mit-mc From: space@mit-mc Newsgroups: net.space Subject: Re: color field for stars Message-ID: <1122@mordor.UUCP> Date: Sun, 17-Mar-85 18:43:09 EST Article-I.D.: mordor.1122 Posted: Sun Mar 17 18:43:09 1985 Date-Received: Wed, 20-Mar-85 03:58:30 EST Sender: daemon@mordor.UUCP Lines: 16 From: Mike Caplinger B-V is the difference between the magnitude of the star when measured through a "blue" filter (440 nm) and a "visual" filter (yellow-green, 548 nm). The difference can be used to determine the star's temperature, since it defines two points on the blackbody curve, via the equation B - V ~ 7000(1/T - 1/15000) (units of Kelvins) (The 15000K comes from the fact that for a star of spectral class A0V B = V by definition.) Alas, stars are often not blackbodies. - Mike