Red clump

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The Red Clump is a region on the Hertzsprung-Russell diagram occupied primarily by metal-rich red giant stars. It is above/right relative to the main sequence and so consequently stars here are brighter than main sequence stars of the same surface temperature (or colder than stars of comparable luminosity). This period in a star's evolution corresponds to the core helium burning phase, unlike the main sequence stars that are burning hydrogen in their cores.

In theory the absolute luminosities of stars in the red clump are fairly independent of stellar composition or age so that consequently they make good standard candles for estimating astronomical distances both within our galaxy and to nearby galaxies and clusters.

[edit] External links

• Krzystof Stanek's page on Red Clumps used for distance measurement