A distant galaxy dies as astronomers watch

INA – SOURCES

Galaxies die when the stars that live in them stop forming. Now, for the first time, astronomers have witnessed this phenomenon in a distant galaxy.

Scientists were able to glimpse a galaxy as it ejected almost half of the gas it uses to form stars. They captured this rare observation using the Atacama Large Millimeter/submillimeter Array of telescopes in Chile.

The light from this galaxy, known as ID2299, has taken about nine billion years to reach Earth. That means astronomers are essentially observing how it appeared when the universe was only 4.5 billion years old (it's now an estimated 14 billion years old).

The ID2299 galaxy is losing 10,000 suns-worth of gas per year, which is diminishing the fuel it needs to form stars by removing 46% of the galaxy's total cold gas so far.

But the galaxy is still quickly forming stars at a rate that is hundreds of times faster than our own Milky Way, which will use up the rest of the gas in the galaxy. This will effectively cause ID2299 to die in a few tens of million years.

The study published Monday in the journal Nature Astronomy.

"This is the first time we have observed a typical massive star-forming galaxy in the distant Universe about to 'die' because of a massive cold gas ejection," said Annagrazia Puglisi, lead study researcher and postdoctoral research associate from Durham University in the UK and the Saclay Nuclear Research Centre in France, in a statement.