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| | Alnilam (Site not responding. Last check: 2007-10-17) |
 | | Though all three stars have similar colors, classes, and temperatures, Alnilam, a hot B (B0) bright supergiant, is notably the most luminous: it is brightest even though farthest away, half again farther than the other two (which lie at nearly the same distance, about 870 light years). |
 | | From Alnilam's measured (though rather uncertain) distance of 1340 light years, it spectacularly radiates (after correction for its great amount of ultraviolet light) 375,000 solar luminosities from its 25,000 Kelvin surface, and is so hot that it illuminates its own (faint) nebulous cloud from the surrounding interstellar gases. |
 | | Alnilam has served for many years as a "standard star" against which to compare others. |
| www.astro.uiuc.edu /~kaler/sow/alnilam.html (344 words) |
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