Meissa, which comes from the Arabic for "white spot" or "shining," is the star that occupies where one would imagine Orion has his head. The star is young, hot, and massive. Because it is very hot, it emits enough ultraviolet light to turn all the hydrogen atoms within 100 light years of the star into ions. Thus, one finds very little hydrogen atoms within a large ring surrounding Meissa. This ring is easily seen in most of the images of Orion in this tour.
Many of the other bright stars in Orion (for example, the belt stars) are at the same distance as Meissa. Probably Meissa and these other stars formed out of the molecular clouds astronomers have found in Orion. In fact, the molecules outside the ring of ions probably are the remnants of the cloud from which Meissa formed. The energy Meissa has dumped back into space was enough to break up and scatter the molecular cloud from which the star formed.
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© Ronald J. Maddalena 1998