WHAT ARE OPEN CLUSTERS? Open clusters are groups of tens, hundreds or thousands of stars originated in the same cloud of gas. Often the gas is gone, in whole or in part, because the radiation emitted by the brightest stars and his appearance is that of an irregular splash of bright spots, with no general structure and asymmetric. The hosted stars are generally young (a few hundred million years; compare with the 4,000 million of the Sun), massive and very hot. They are scattered on sizes in the order of thirty light-years, and are slowly dispersed by the tidal […]