O-type Star

Alnitak
Image from Steve Bowers

The O type star is the first and brightest in the sequence of spectral types, and is distinguished by lines of ionized helium. Often neutral helium and weak hydrogen lines are also visible. An O5 type star generally has a mass of about 40 times that of Sol, a luminosity 405,000 times as great, and and a surface temperature of some 40,000° Kelvin. The star is so hot it burns blue-white in colour.

Being so hot and bright this type of star burns up all its fuel very quickly. When it collapses, having exhausted all its fuel, an O type star will usually become a large black hole. An O5 will spend only about a million years on the main sequence. These stars therefore are very rare, on average about one in every billion cubic light years of space. Only one star in 4 million is an O-type. Despite having an expansive life-zone, O-type stars never have natural life-supporting planets, as they do not endure long enough for life to form. However they are highly prized by development corporations, amat farmers, and stellar engineers.
 
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Development Notes
Text by M. Alan Kazlev

Initially published on 17 December 2001.