What is OB star?
[[File:Morgan-Keenan spectral classification.svg|thumb|300px|O and B stars are the hottest in the [[stellar classification]]. These stars are from the [[main sequence]]]] [[File:LH 72 HST.jpg|250px|thumb|[[LH 72]] is one of the OB associations present in the [[Large Magellanic Cloud]].]] '''OB stars''' are hot, massive blue [[star]]s. They are stars of types O or B in the [[Hertzsprung{{ndash}}Russell diagram]]. Like other [[giant star]]<nowiki/>s they are short lived, and do not move far from where they were formed. During their lifetime, they emit huge amounts of [[ultraviolet radiation]]. This radiation [[ionization|ionizes]] the surrounding interstellar gas of the [[nebula]], forming an [[H II region]]. == References == *{{cite journal | url=http://www.iop.org/EJ/article/1538-3881/125/5/2531/203021.html | author=B. Cameron Reed | title=Catalog of galactic OB stars | journal=The Astronomical Journal | volume=125 | year=2003 | issue=5 | pages=2531–2533 | doi=10.1086/374771 | bibcode=2003AJ....125.2531R| s2cid=121285799 }} ==Other websites== * Scientia Astrophysical Organization's star classification page. [http://www.astrophysical.org/starclassification.php] {{Webarchive|url=https://web.archive.org/web/20060129055121/http://www.astrophysical.org/starclassification.php |date=2006-01-29 }} * Philippe Stee's homepage: [http://www.oca.eu/stee/page1/page3/page3.html Hot and active stars research] {{science-stub}} [[Category:Types of stars]]