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BBC reports that results of a study of the spectrum of light emitted by 23,000 red, passive galaxies and 4,000 blue, star-forming ones shows that when galaxies stop making stars, their death is usually a slow process that chokes them of the necessary cool gases over about four billion years. Astronomers surveyed thousands of galaxies, living and dead, to assess whether the transition is rapid or slow. In the dead galaxies they detected high levels of metals, which build up during star formation and point to a slow strangulation process. "Metals are a powerful tracer of the history of star formation: the more stars that are formed by a galaxy, the more metal content you'll see," says Dr Yingjie Peng. "So looking at levels of metals in dead galaxies should be able to tell us how they died."
Astronomer Andrea Cattaneo from the Observatoire de Paris compares this tell-tale evidence to the high levels of carbon dioxide seen in a strangled human body. "During [strangulation], the victim uses up oxygen in the lungs but keeps producing carbon dioxide, which remains trapped in the body," wrote Dr Cattaneo. "Instead of building up CO2, the strangled galaxies accumulate metals - elements heavier than helium - produced by massive stars." On average, living, star-forming galaxies were four billion years younger than the dead ones. This matches the amount of time that the astronomers calculate would be needed for the galaxies to burn up their remaining gas supply during the strangulation. "This is the first conclusive evidence that galaxies are being strangled to death," says Peng. "What's next though, is figuring out what's causing it. In essence, we know the cause of death, but we don't yet know who the murderer is, although there are a few suspects."
(Score: 3, Insightful) by maxwell demon on Friday May 15 2015, @07:07AM
A person when not strangled gets new oxygen and gets rid of CO2 by breathing air, and the air gets new oxygen and gets rid of CO2 through plants. If there were no plants removing CO2 and adding oxygen, all oxygen-breathing life would soon be gone because the earth as a whole would suffocate, without being strangled by anyone.
So what would be the process that resupplies the galaxies with "fresh air" if not "strangulated"? If there's no such mechanism, it's not strangulation, it's just using up all the "air" that's available.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by SlimmPickens on Friday May 15 2015, @07:53AM
bacteria
(Score: 4, Insightful) by FatPhil on Friday May 15 2015, @09:01AM
But this is also like dieing a slow death suffocated of your own byproducts - so you've drowned in bathtub of your own piss and poo.
Or maybe we don't need stupid human-oriented analogies and should just stick to the science itself being interesting without personifying everything.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 1) by patrick on Friday May 15 2015, @10:57AM
Or maybe we don't need stupid human-oriented analogies
But they make us amazing! [smbc-comics.com]
(Score: 2) by FatPhil on Friday May 15 2015, @11:23AM
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 1) by OrugTor on Friday May 15 2015, @04:33PM
Thank you! I too am tired of the foolish personification and exaggeration that passes for science writing these days.
(Score: 0) by Anonymous Coward on Friday May 15 2015, @03:58PM
The word you're looking for is "asphyxiation".