For other uses, see Class O.

An example of an O-class star.

An O-class (or O-type) star is a stellar classification for stars composed of ionized atoms, especially helium, emitting high amounts of ultraviolet radiation, generally referred to as being blue-violet or dark blue in color. O-type stars in the main sequence tend to be extremely hot in temperature (in the neighborhood of 28,000 to 50,000 Kelvin) and bright in terms of absolute magnitude, the "dark" and "violet" descriptors of their name are as such because of the large output of non-visible heat radiation. (ST reference: Star Charts)

O stars[edit | edit source]

Connections[edit | edit source]

Stellar classification
By class and type class O blue-violet starclass B blue starclass A blue-white starclass F white star (white dwarf) • class G yellow star (yellow dwarfyellow giant) • class K orange star (orange giant) • class M red star (red dwarfred giant) • boson starbrown dwarfgreen starN-type starR-type starS-type starD-type star
By size or makeup black hole/black starcarbon stardwarf star (brown dwarfred dwarfwhite dwarfyellow dwarf) • giant star (blue giantred giantorange giantyellow giant) • Lazarus starmicrostarneutron star (collapsarmagnetarpulsar) • protostarsupergiant starvariable starwhite holeWolf-Rayet star
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