Stellar Population

Stars are divided into two populations based on their metallicity. The metallicity of a star is the measure of how much of that star is composed of heavy elements (heavier than helium). Population I (metal-rich stars) and Population II stars (metal-poor stars). The sun is an Intermediate Population I star.

Population I stars are located in and around the galactic bulge of a galaxy, as well as in the spiral arms of a spiral galaxy. Population II stars are found in the galactic halo region.

Findings suggest that more planets (particularly giant planets) would be located around Population I stars than around Population II stars, although this is not well understood.