Friday, October 19, 2012

Stellar Populations

Stellar populations are groups of stars classified by astronomers according to their metal content or metallicity. So, the first stars that appeared in the universe, having a low metal content, are categorized as Population III; they are pair-instability supernovae that have exhausted much of their energy. Population II are second generation of stars which also arose early in the history of a galaxy from hydrogen and helium; red giants belong to this group. The newest stars in a galaxy belong to Population I and they formed from the debris of exploding Population II stars.