For the first time in history, astronomers were able to witness the previously unknown phenomenon of a galaxy’s life coming to an end. Galaxies die when the stars that live within them stop forming.
Using the Atacama Large Millimeter/submillimeter Array of telescopes in Chile scientists were able to watch as a distant galaxy ejected half of the gas it uses to form stars. The galaxy is specifically known as ID 2299, and the light emitted from the stars within this galaxy took about nine billion years to reach Earth.
Based on this timing, astronomers determined that they’re currently witnessing cosmic events that occurred when the universe was only 4.5 billion years old; the universe is thought to be 14 billion years old for context.
The galaxy is thought to be losing around 10,000 suns-worth of gas per year. This is significant because that gas is what’s needed for the galaxy to produce new stars. So far astronomers believe ID2299 has lost about 46% of its cold gas, however, the galaxy is still able to quickly form stars at rates greater than what we experience in our own Milky Way galaxy.
Since ID2299 is still able to successfully produce stars, it’s likely that it won’t die for another few tens of millions of years. Annagrazia Puglisi, lead study researcher and postdoctoral research associate from Durham University in the UK and the Saclay Nuclear Research Center in France, spoke to the press after publishing the study in the journal of 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.”
According to Puglisi, it’s also possible that ID2299’s demise is the result of a collision with another galaxy. Astronomers observed a large stream of gas and stars that typically only forms when two galaxies come together in a collision, and normally these streams are too far and faint to be seen, however, the scientists ability to see this tail means that the galaxy was likely formed by some sort of collision.
If a collision is what is causing this galaxy’s demise, astronomers will need to reconsider existing theories regarding the life cycle of stars and their formation at the end of a galaxy’s “life.” Previous theories claimed that the winds created by star formations would combine with active black holes at the center of a galaxy, which would thus send out materials needed to form stars.
“Our study suggests that gas ejections can be produced by mergers and that winds and tidal tails can appear very similar. This might lead us to revise our understanding of how galaxies ‘die,’” said Emanuele Daddi, study coauthor and astronomer at the Saclay Nuclear Research Centre in France.
Astronomers were actually working on a survey regarding cold gas in distant galaxies when they noticed the tidal tail of ID2299 and realized just what they were witnessing. Future observations of the galaxy will likely reveal more about the process of gas being ejected from galaxies and how it impacts star formation, but in the meantime, astronomers are celebrating the fact that they witnessed a cosmic event that they’ve only theorized about in the past.
Eric Mastrota is a Contributing Editor at The National Digest based in New York. A graduate of SUNY New Paltz, he reports on world news, culture, and lifestyle. You can reach him at firstname.lastname@example.org.