dipper@utastro.UUCP (Debbie Byrd) (01/16/86)
The three stars in the belt of Orion are all very far away. More -- after this. January 16 The Belt of Orion A listener asked us to talk about the three medium-bright stars that represent the belt of Orion. These three stars make the constellation Orion easy to identify -- since they form a short, straight row -- now in the south each evening. The three belt stars in Orion are famous for being the belt. But they're not so well known as individuals. Strangely enough, the three are actually somewhat related in space. They're all located at about the same very great distance -- between 15 and 16 hundred light-years away. To be this far away and still visible, the three belt stars must be intrinsically large and bright. Near each other in space, they are three giants in the general stream of smaller stars orbiting the center of the galaxy. These three proud stars have names. The westernmost star is Mintaka. The central star is Alnilam. And the eastern one is Alnitak. The central star in the belt of Orion is huge and solitary. But the other two stars are both doubles -- arranged at different random angles from each other, so that we see them differently. In fact, you wouldn't know the western star was double - until a periodic dimming of its light revealed the unseen companion. When the fainter star wheels in front of the brighter one, light from the Mintaka system fades. The eastern star in Orion's belt has a companion we can see through telescopes - and a pretty sight it is, with one star yellow and the other blue. Script by Deborah Byrd. (c) Copyright 1985, 1986 McDonald Observatory, University of Texas at Austin