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Galaxies Die By Slow "Strangulation"
HughPickens.com writes: 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."
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."
Maybe she likes it...?
"Strangulation" seems to me an over-dramatic way of putting it. "Starvation" would be better. The supply of fresh hydrogen stops, so new stars stop being created. The old stars continue burning, some go supernova and blast out metals.Like when you stop adding wood to a fire, the logs already on the fire continue burning and the amount of ash increases.
All this suggests that there is not an indefinite supply of intergalactic hydrogen, so once the galaxy has pulled in all the hydrogen in its immediate vicinity, it will slowly starve.
Consciousness is an illusion caused by an excess of self consciousness.
Onwards to mine strangulation murdered galaxies! We need to start constructing a galaxy class Dyson sphere as the universe expands.
The cause is ... them using up all the hydrogen/helium by fusing it into metals so there is no more fuel for stars? Like they just said?
I can't tell if I'm missing something or they are just incredibly dense.
To compare the natural long term maturity of a galaxy to the very short term and violent strangulation of a person is both offensive and the opposite of informative.
is "Let there be Light".
The USA is only 4X older than me...perspective
I hate to break it to these esteemed scientists but the finite supply of matter in a galaxy (and energy) therefore means that the end result must be one where eventually it has progressed to a point where the galaxy no longer has enough new material to "burn."
i.e. eventually the entropy for a galaxy will reach a maximum value.
What about battery failure? I have only had my Galaxy Note 3 for two and a half years so it hasn't happened yet
Why do astronomers use the word "metal" to mean anything heavier than helium? I get that there's a lot of hydrogen and helium out there, and it might be useful to distinguish those from everything else but... why "metal"? Is it just that nobody mentioned that that word was already in use or is there a better reason that that?
David Carradine approves.
The devil made me do it
During strangulation, the jugular vein is pressed shut, leading to vascular congestion in the brain (which is how you get the telltale petechiae); the backpressure eventually prevents the influx of oxygenated blood to the brain, which is subsequently starved of oxygen. It's actually quite difficult to squeeze somebody's windpipe shut.
(Do you really *want* to know why I know this?)
1) just to be clear, when he says "metals" are everything more than helium, that's an astronomer thing.
2) IANAA, but the whole 'stellar starvation' thing seems logically obvious due to the iron peak - as galaxies feed on their hydrogen, their suns fuse it up all the way to iron, then they no longer are generating energy from subsequent fusion, merely consuming it (elements above iron are normally only created persistently from supernovae), ergo, once a galaxy has climbed the fusion-energy curve up to iron, beyond that it's go nowhere to go except collapse and ultimate I'd guess black hole status?
-Styopa
How very "Rock and Roll"!
Chas - The one, the only.
THANK GOD!!!
"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."
It was Colonel Mustard with the rope in the Virgo Supercluster.
What if the galaxy with many fewer stars has higher quality stars? Should we give so much credit to galaxies that are prolific star creators when they have poached the material from other galaxies?
Sounds like Alzheimer's disease. Materials that are not useful and build up in a healthy system, causing the breakdown or choking off of the normal process. And it doesn't sound like there's a cure for galaxies, either, other than a "Big Crunch" flushing mechanism (which has been generally dismissed).
If more galaxies are red than blue (and I blue stars don't last all that long) how close are we to heat death?
It's silly to talk about galaxies this way. Not to mention, older galaxies like this are probably much MORE likely to harbor LIFE.