Exploding Stars May Have Caused Mass Extinction On Earth, Study Shows (phys.org) 30
schwit1 shares a report from Phys.Org: A new study led by University of Illinois, Urbana-Champaign astronomy and physics professor Brian Fields explores the possibility that astronomical events were responsible for an extinction event 359 million years ago, at the boundary between the Devonian and Carboniferous periods. The paper is published in the Proceedings of the National Academy of Sciences. The team concentrated on the Devonian-Carboniferous boundary because those rocks contain hundreds of thousands of generations of plant spores that appear to be sunburnt by ultraviolet light -- evidence of a long-lasting ozone-depletion event.
"Earth-based catastrophes such as large-scale volcanism and global warming can destroy the ozone layer, too, but evidence for those is inconclusive for the time interval in question," Fields said. "Instead, we propose that one or more supernova explosions, about 65 light-years away from Earth, could have been responsible for the protracted loss of ozone." The team explored other astrophysical causes for ozone depletion, such as meteorite impacts, solar eruptions and gamma-ray bursts. "But these events end quickly and are unlikely to cause the long-lasting ozone depletion that happened at the end of the Devonian period," said graduate student and study co-author Jesse Miller.
A supernova, on the other hand, delivers a one-two punch, the researchers said. The explosion immediately bathes Earth with damaging UV, X-rays and gamma rays. Later, the blast of supernova debris slams into the solar system, subjecting the planet to long-lived irradiation from cosmic rays accelerated by the supernova. The damage to Earth and its ozone layer can last for up to 100,000 years. However, fossil evidence indicates a 300,000-year decline in biodiversity leading up to the Devonian-Carboniferous mass extinction, suggesting the possibility of multiple catastrophes, maybe even multiple supernovae explosions. "This is entirely possible," Miller said. "Massive stars usually occur in clusters with other massive stars, and other supernovae are likely to occur soon after the first explosion." "I'm sure somebody has a GRB or similar in their 2020 pool of what could go wrong next," adds schwit1.
"Earth-based catastrophes such as large-scale volcanism and global warming can destroy the ozone layer, too, but evidence for those is inconclusive for the time interval in question," Fields said. "Instead, we propose that one or more supernova explosions, about 65 light-years away from Earth, could have been responsible for the protracted loss of ozone." The team explored other astrophysical causes for ozone depletion, such as meteorite impacts, solar eruptions and gamma-ray bursts. "But these events end quickly and are unlikely to cause the long-lasting ozone depletion that happened at the end of the Devonian period," said graduate student and study co-author Jesse Miller.
A supernova, on the other hand, delivers a one-two punch, the researchers said. The explosion immediately bathes Earth with damaging UV, X-rays and gamma rays. Later, the blast of supernova debris slams into the solar system, subjecting the planet to long-lived irradiation from cosmic rays accelerated by the supernova. The damage to Earth and its ozone layer can last for up to 100,000 years. However, fossil evidence indicates a 300,000-year decline in biodiversity leading up to the Devonian-Carboniferous mass extinction, suggesting the possibility of multiple catastrophes, maybe even multiple supernovae explosions. "This is entirely possible," Miller said. "Massive stars usually occur in clusters with other massive stars, and other supernovae are likely to occur soon after the first explosion." "I'm sure somebody has a GRB or similar in their 2020 pool of what could go wrong next," adds schwit1.
359 mo years ago (Score:2)
Re: (Score:3)
Dinosaurs were still 10's of millions of years in the future.
https://www.newscientist.com/a... [newscientist.com]
Re: (Score:2)
I wouldn't count it as speculation. The data seem to indicate the usual terrestrial suspects don't have the right fingerprints for the extinction. Hence, the search for other suspects. They ruled out some cosmic suspects but ruled in possible others. Now research can treat those as hypotheses and work to validate or invalidate them. Sounds like typical a research program to me.
Re: (Score:2)
That's how you find different possible explanations to a phenomenon. Later you study them better to find if they are all valid and how probable they are.
Re:Pure speculation (Score:4, Informative)
The team said the key to proving that a supernova occurred would be to find the radioactive isotopes plutonium-244 and samarium-146 in the rocks and fossils deposited at the time of extinction.
Re: (Score:2)
Do I get this right?
No, you don't.
Re: (Score:2)
You know what's really great about YAML? No, I don't either.
Could be worse. XML for example.
I know. Tragic, isn't it?
Fermi Paradox (Score:3, Interesting)
Re: (Score:3)
Re: (Score:2, Funny)
And lots of freeze dried and canned food and water to last a few hundred thousand years..
Re:Fermi Paradox (Score:4, Interesting)
Well, for this one what you need it undersea cities that don't need support from land based civilization. Most of what they're talking about would be countered by a good blanket of water. So if there was a die-off of ocean based life at that time, it means that their explanation is probably wrong. Of course, food chains are complex, and you'd expect a minor extinction event even among oceanic creatures, but nothing major. On land you'd expect something major. Burrowing creatures might survive, but their food supply won't do as well.
Re: (Score:1)
sterilization events (Score:1)
I recall reading an analysis suggesting there are x-ray beacons from supernovae bright enough to create a sterilization event anywhere in space, including on Earth every 100 million years or so. If true, that would go a long way toward explaining why we haven't seen evidence of E.T.
great, now the climate change deniers can come up (Score:1)
Re: (Score:2, Interesting)
I'm a denier, or what you'd call one... But we don't deny CO2's effect, only that man made sources of CO2 are not the primary cause of climate change. But I don't deny climate change is happening, only that it's not as dire of a situation as we are told.
I'm not convinced that the effects of climate change can be controlled by man and the wholesale economic damage the proposed solutions to address climate change are unwise (if not pointless). In general, I see the wanton destruction of our economy and the
Re: (Score:1)
Re: (Score:2)
...and the wholesale economic damage...
Have you seen Tesla stock lately?
nah, supernovas have remains (Score:2)
Re: (Score:2)
There would be remnants
" Guilty" ones?
Re: (Score:2)
Everything plus everything equals zero (Score:2)
Sounds like earth was attacked (Score:1)
Actually this size is frequent and evaporates (Score:2)
Check out this informative article on 2020 QG which is what it's called.
Apparently meteorites of this size hit our atmosphere multiple times per year and always vaporize high in the atmosphere.
https://earthsky.org/space/clo... [earthsky.org]