Editing Stellar evolution (section)

===Brown dwarfs and sub-stellar objects===
{{Main|Brown dwarf}}
Protostars with masses less than roughly {{convert|0.08|solar mass|kg|abbr=on}} never reach temperatures high enough for [[nuclear fusion]] of hydrogen to begin. These are known as [[brown dwarf]]s. The [[International Astronomical Union]] defines brown dwarfs as stars massive enough to [[deuterium burning|fuse deuterium]] at some point in their lives (13 [[Jupiter mass]]es ({{Jupiter mass|link=y}}), 2.5&nbsp;&times;&nbsp;10<sup>28</sup>&nbsp;kg, or {{Solar mass|0.0125}}). Objects smaller than {{Jupiter mass|13}} are classified as [[sub-brown dwarf]]s (but if they orbit around another stellar object they are classified as planets).<ref>{{cite web|title=Working Group on Extrasolar Planets: Definition of a "Planet" |work=IAU position statement |date=2003-02-28 |url=http://www.dtm.ciw.edu/boss/definition.html |access-date=2012-05-30 |url-status=dead |archive-url=https://web.archive.org/web/20120204173630/http://www.dtm.ciw.edu/boss/definition.html |archive-date=February 4, 2012 }}</ref> Both types, deuterium-burning and not, shine dimly and fade away slowly, cooling gradually over hundreds of millions of years.