Astronomers have seen a distant galaxy begin to die, which could be a major breakthrough in our understanding of space.
Galaxies begin to “die” when they stop forming stars. Astronomers have observed a wide range of such dead galaxies scattered throughout the universe – but have not been able to say exactly why.
Astronomers now have a clear idea of such a spectacular event and hope that it can shed light on the process that causes galaxies to die.
The observed galaxy loses about 10,000 gasolines worth 10,000 suns a year, which means it runs out of fuel to create new stars. It has now lost almost half of that gas, and because it is still creating stars at speeds hundreds of times faster than our Milky Way, it will deplete the remains of tens of millions of years and disappear as it does.
Because the galaxy is 9 billion light-years away, astronomers are actually looking at events that occurred in the relative youth of the universe, when the cosmos was only 4.5 billion years old.
Astronomers believe that the dramatic death was caused by a collision with another galaxy, which potentially changes our understanding of how events can happen.
As the two galaxies collided, they joined to create the one observed by astronomers, called ID2299. Evidence of the collision was found in the form of a “tidal tail” – a long stream of stars and gas that extends into interstellar space.
Such clues are usually too dark to be seen in distant galaxies. But researchers caught him by accident, just when he was released, and so they were able to identify him.
The death of galaxies occurs when their star-forming material is ejected into space, leaving it without the material needed to create new stars. Until now, most astronomers believed that this was due to the winds that erupt when stars form and the black holes that sit in the center of the galaxy.
However, new research shows that such collisions can kill them as well.
The new document also suggests that the two events can be easily mixed: when gas emissions are caused by mergers and leave tidal tails behind, they may look similar to those wind-induced deaths. As such, previous research, which appears to have focused on winds, could actually observe tidal tails all the time, the researchers said, and previous work may need to be re-evaluated.
The study was reported in a new paper, “Titanic interstellar ejection from a massive galaxy of a stellar burst at z = 1.4,” published in Natural astronomy.