Bok globules

Bok globules are dense, cold clouds (a few kelvins) of gas and dust containing 10 to 50 solar masses with a diameter of the order of a light-year. They were observed in 1940 by the Dutch-American astronomer Bart Bok, who had theorised that they were regions undergoing gravitational collapse leading to the formation of stars. At the beginning of the 1990s, near infrared observations confirmed this hypothesis.