What is Yellow hypergiant?
{{no sources|date=November 2018}} [[Image:HR-vartype.svg|right|upright=1.4|thumb|Intrinsic variable types in the [[Hertzsprung–Russell diagram]] showing the Yellow Hypergiants above (i.e. more luminous than) the Cepheid [[instability strip]].]] A '''yellow hypergiant''' is a huge [[hypergiant]] [[star]]. It starts off a mass of about 20–60 [[solar mass]]es, but it soon loses about half that mass (because they are very [[unstable]]). It has a [[spectral class]] from A to K. They are amongst the most [[luminous]] stars, with [[absolute magnitude]] (M<sub>V</sub>) around &minus;9. They are very rare: only 15 are known in the [[Milky Way]] and six of those are in [[Westerlund 1|a single cluster]]. They are sometimes referred to as 'cool hypergiants' in comparison to O- and B-type stars, and sometimes as 'warm hypergiants' in comparison to [[red giant|red supergiant]]s. Yellow hypergiants have evolved off the [[main sequence]] and have little hydrogen left in their centres. ==Examples== * [[Rho Cassiopeiae]] * [[V509 Cassiopeiae]] * [[V382 Carinae]] * [[HR 5171]] [[Category:Hypergiants]] [[Category:Types of stars]] {{physics-stub}} {{sci-stub}}