Stars do not form in isolation. During gravitational collapse, molecular clouds fragment, forming a large number of stars. For this reason, young stars are typically observed as members of star clusters or associations. In the past decade, the study of stellar clusters in the Milky Way has undergone a revolution, thanks to observations from the Gaia satellite of the
After their formation, during the first few million of years (how many? it depends on the mass: the larger the stellar mass the faster is their evolution) stars continue to contract under their the action of their own gravity, rising their temperature and density. During this phase, their nuclei have not started yet the thermonuclear reactions that will power the
Massive stars are enormous chemical laboratories where heavy chemical elements are synthesized. For instance, the alpha-elements (O, Mg, Si, Ca, and Ti) are produced by nucleosynthetic processes in the interior of massive stars. Moreover, the lifetime of massive stars is much shorter than that of low mass stars: few million years for the former compared to several billion of years
di Mario Giuseppe Guarcello ( segui mguarce) Esistono vari modelli che cercano di spiegare la formazione e l’evoluzione del disco sottile della Via Lattea, della sua popolazione stellare e dei bracci a spirale. Uno dei parametri fondamentali per il processo di formazione stellare nel disco, la distribuzione di massa delle stelle, l’evoluzione stellare e la migrazione lungo il disco
