Segue 3とは 意味・読み方・使い方

Segue 3 is a faint globular cluster of the Milky Way galaxy discovered in 2010 in the data obtained by Sloan Digital Sky Survey. It is located in the Pegasus constellation at the distance of about 16 kpc from the Sun. Its small radius—of about 1.5 pc—is typical for globular clusters. Segue 3 is an extremely faint—its visible absolute magnitude is only −1.2, which means that the cluster is only 250 times brighter than the Sun. The metallicity of Segue's 3 stars is [Fe/H] < −2.3, which means that they contain at least 200 times less heavy elements than the Sun. Segue 3 appears to be one of the fainest globular clusters of the Milky Way.