An international team of scientists led by the University of Durham (United Kingdom) has found out why green galaxies are so rare in our universe, since, unlike these, red and blue galaxies are very frequent: in the blue ones, many stars and planets are being born; in the red ones, old stars lie that begin to burn ; but the green ones … they are peculiar and not frequent.
What causes these green galaxies to appear?
Thanks to a new computer simulation in order to investigate the colors of the galaxies and find out what information they could give us about their evolution, the scientists modeled the ages of the stars in the galaxies and what they were made of, precisely by the color of light they emit.
According to the department of Computational Cosmology, green galaxies are prone to being at a critical stage in their evolution, when they rapidly turn from blue to red. Thus, the green color would represent a relevant intermediate state in its evolution.
“Galaxies give off a healthy blue glow when new stars and planets are being born. However, if star formation stops, galaxies turn red as stars begin to age and die. Because stars are formed from dense gas, it takes a powerful process to quickly destroy their gas supply; immediately stop their star formation and cause such a dramatic change in their color, ”explained James Trayford, study leader at the National Astronomy Meeting in Nottingham.
“We found that smaller green galaxies are routinely being violently shaken by the gravitational pull of a massive neighbor , causing them to be stripped of their gas supply at a distance,” continues Trayfod.
The scientists, who have named this project EAGLE (Evolution and assembly of galaxies and their environments), explain that in this situation, green galaxies tend to self-destruct , but “some lucky galaxies” are capable of absorbing a new supply. of gas from its environment, reactivating the formation of stars and planets, galaxies and later restoring them to a healthy blue state.
