Glossary term: O-type Star

Also known as O star or O-type star

Description: An O star is one whose "surface" temperature (the temperature of the layer in the star from which its light is emitted also known as effective temperature) is greater than approximately 30,000 kelvins. An O-star is identified by the absorption lines in its spectrum including ionized helium lines. O stars are the hottest and bluest of the main spectral classifications. O stars on the main sequence have the shortest hydrogen burning lifetime and as a result are mostly found in and around star forming regions.

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Term and definition status: This term and its definition is still awaiting approval

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".