Astronomers can see a distant galaxy die as it blows cold gas into space.
Such gas is essential for the formation of stars. Galaxies die when they can no longer do so.
This galaxy was formed by a collision in which two galaxies merged into one. It left a “tail” that emits 10,000 solar gases each year.
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For the first time, astronomers can clearly see a galaxy begin to die.
Nine billion light-years away, the galaxy ID2299 loses critical cold gas that helps create new stars. Every year, enough gas bleeds out to create 10,000 suns. It has already lost almost half of its cold gas. The rest is used up to form new stars at a pace hundreds of times faster than on the Milky Way.
At this speed, the galaxy will soon run out of extra gas and will not be able to create new stars. For a galaxy, it’s death.
The team of scientists who discovered ID2299 and its impending death published their findings Monday in the journal Nature Astronomy.
They believe that ID2299 was formed after two galaxies collapsed and merged, creating a new galaxy. This resulting galaxy has a revealing “tidal tail” from which streams of stars and interstellar material pull out into space.
Tide tails often form when the outer layers of galaxies are removed, when they merge. Such tails in distant galaxies are usually too faint for astronomers on Earth to see, even though they have been discovered in hundreds of galaxies. Scientists saw this just as it began to stretch out into space. This is where all the gas escapes.
The finding suggests that larger collisions may leave galaxies leaking vital gases into space, a process that eventually starves them and stops star formation, thereby killing them.
“This is the first time we are observing a typical massive star-forming galaxy in the distant universe by ‘dying’ due to a massive cold gas exhaust,” Annagrazia Puglisi, the study’s lead author and researcher at Durham University in England, said in a press release.
More than one way to ‘die’
When stars form, they produce wind. Scientists believe that there is a black hole in the center of any massive galaxy, which also produces wind when it consumes material that falls into its gravity. Astronomers believe that these winds from stars and black holes carry star-forming material into outer space and eventually cause galaxies to die.
But the discovery of ID2299’s gas-leaking tail reveals a new path to galactic death.
“Our study suggests that gas emissions can be produced by mergers, and that wind and tidal halls may seem very similar,” said Emanuele Daddi, a co-author of the study and an astrophysicist at the Saclay Nuclear Research Center in France, in the release. “This may lead us to revise our understanding of how galaxies ‘die’.”
The finding could also provide clues as to where our own galaxy is heading. The Milky Way shoots tracts of its own cold gas into the vacuum, and it is also about to collide with the Andromeda galaxy in about 4 billion years.
“Witnessing such a massive disruption event adds an important piece to the complex puzzle of galaxy evolution,” Chiara Circosta, a co-author of the study and researcher at University College London, said in the release.
Scientists stumbled upon this doomed galaxy while studying cold gas in 100 distant galaxies using the Atacama Large Millimeter / Submillimeter Array (ALMA) in the Chilean desert.
“I was eager to learn more about this strange object because I was convinced that there was an important lesson to be learned about how distant galaxies evolve,” Puglisi said.
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