Scientists at Tohoku University (Japan) found that the Milky Way experienced a “clinical death” – a period of cessation of the process of star formation, which lasted about two billion and ended five billion years ago. This model confirms the chemical composition of the now existing stars.
According to the researchers, during its formation the Milky Way attracted the surrounding cold gas, which was the raw material for the formation of the first-generation stars. Supernovae type II, which occur during the collapse of the core of a massive star, released into the interstellar medium such chemical elements as oxygen, calcium, silicon and magnesium. Approximately seven billion years ago, shock waves produced by supernovae heated the gas, and the cold matter ceased to accumulate in the galaxy, which stopped the processes of star formation.
During this period of “clinical death”, supernovae of type Ia, which occur during the explosion of a white dwarf in the composition of double variable stars, occurred. These catastrophic processes led to enrichment of the medium with iron. As the hot gas cooled, emitting radiation, the streams of cold gas gradually renewed, which led to the emergence of stars of the second generation, including the Sun.