Orion OB association

Orion OB association

[ə‚rī·ən ¦ō′bē ə‚sō·shē‚ā·shən]
(astronomy)
A loose, gravitationally unbound grouping of hot massive stars with spectral types A, B, and O, which originated in the giant molecular clouds Orion A and Orion B, together with tens of thousands of low-mass young stars which formed from the Orion molecular clouds.
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