Headline: For the First Time, Astronomers Watch a Galaxy Die
Author: Courtney Balcombe, News Editor
For the first time, astronomers have witnessed a galaxy die. Galaxies start to die when the stars stop forming inside them.
According to CNN, galaxy ID2299, which is nine billion light-years away, ejected almost half of its gases needed to create new stars. Scientists were able to see this using the Atacama Large Millimeter/submillimeter Array (ALMA) of telescopes in Chile.
“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.
The galaxy loses about 10,000 suns-worth of gas per year, making it harder to form stars by removing 46 percent of the galaxy’s total cold gas so far. The galaxy is still forming stars at a higher rate than the Milky Way.
The team of researchers that discovered ID2299, believe that it was formed after two galaxies collided together. The result from the collision left a “tidal tail” which forms when the galaxy’s outer layer is stripped away as the two merge. This can also lead to where the gases are escaping.
“Our study suggests that gas ejections can be produced by mergers and that winds and tidal tails can appear very similar,” said Emanuele Daddi, study coauthor and astronomer at the Saclay Nuclear Research Centre in France. “This might lead us to revise our understanding of how galaxies ‘die.’”
The researchers are planning on conducting future observations of galaxy ID2299 in order to get a better understanding of the mechanism behind the ejected tail of gas. By studying the relationship between the star-forming gas and the galaxy’s eventual death, astronomers are hoping to understand how galaxies evolve over time until they stop giving birth to stars, and die.
As the galaxy continues to create stars at its rate, ID2299 will meet its demise in a few tens of million years.
PHOTO Description: This artist’s impression of ID2299 shows the galaxy, the product of a galactic collision, and some of its gas being ejected by a “tidal tail” as a result of the merger. New observations made with ALMA, in which ESO is a partner, have captured the earliest stages of this ejection, before the gas reached the very large scales depicted in this artist’s impression.
