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from the supernovae-have-that-effect-on-planets dept.
Researchers consider whether supernovae killed off large ocean animals at dawn of Pleistocene
About 2.6 million years ago, an oddly bright light arrived in the prehistoric sky and lingered there for weeks or months. It was a supernova some 150 light years away from Earth. Within a few hundred years, long after the strange light in the sky had dwindled, a tsunami of cosmic energy from that same shattering star explosion could have reached our planet and pummeled the atmosphere, touching off climate change and triggering mass extinctions of large ocean animals, including a shark species that was the size of a school bus.
[...] The effects of such a supernova — and possibly more than one — on large ocean life are detailed in a paper just published in Astrobiology.
[...] A supernova 2.6 million years ago may be related to a marine megafaunal extinction at the Pliocene-Pleistocene boundary where 36 percent of the genera were estimated to become extinct. The extinction was concentrated in coastal waters, where larger organisms would catch a greater radiation dose from the muons.
According to the authors of the new paper, damage from muons would extend down hundreds of yards into ocean waters, becoming less severe at greater depths: "High energy muons can reach deeper in the oceans being the more relevant agent of biological damage as depth increases," they write.
Indeed, a famously large and fierce marine animal inhabiting shallower waters may have been doomed by the supernova radiation.
"One of the extinctions that happened 2.6 million years ago was Megalodon," Melott said. "Imagine the Great White Shark in 'Jaws,' which was enormous — and that's Megalodon, but it was about the size of a school bus. They just disappeared about that time. So, we can speculate it might have something to do with the muons. Basically, the bigger the creature is the bigger the increase in radiation would have been."
Megalodon (Carcharocles megalodon).
Hypothesis: Muon Radiation Dose and Marine Megafaunal Extinction at the End-Pliocene Supernova (DOI: 10.1089/ast.2018.1902) (DX)
(Score: 3, Interesting) by HiThere on Friday December 14 2018, @07:34PM (2 children)
Uranium is too common for the source to be an event both that rare and that small. A galactic core explosion might to it, or smaller or more common phenomenon.
FWIW, the normal percentages of elements cause me to think that we might live in a second generation galaxy.
P.S. Reply to a post further above...
First generation (in the universe) stars would have only Hydrogen and Helium, and scant, scant, scant traces of heavier elements to work with. OTOH, I accept that first generation (in this galaxy) stars would have a much richer blend. I think the term "first generation stars" is used in a confusingly ambiguous way, sometimes meaning one of those concepts and sometimes the other.
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(Score: 3, Interesting) by legont on Friday December 14 2018, @09:21PM (1 child)
It's the first time I've heard about "galactic core explosion". https://www.starburstfound.org/superwave/Galactic.html [starburstfound.org]
How close is this to the mainstream? The article above implies rather frequent showers from our center. Way more frequent than supernovas in the vicinty.
"Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.
(Score: 3, Interesting) by HiThere on Saturday December 15 2018, @12:27AM
Well, really I should have referred to "Seyfert Galaxies" or some such, but Niven's phrase stuck in my memory, even if he was quite wrong. (He wasn't attempting to be right, just plausible and interesting...which it was.)
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