First Evidence of Supernovae Found In Ice Cores 145
KentuckyFC writes "Supernovae in our part of the Milky Way ought to have a significant impact on the atmosphere. In particular, the intense gamma-ray burst would ionize oxygen and nitrogen in the mid to upper atmosphere, increasing the levels of nitrogen oxide there by an order of magnitude or so. Now a team of Japanese researchers has found the first evidence of a supernova's impact on the atmosphere in an ice core taken from Dome Fuji in Antarctica. The team examined ice that was laid down in the 11th century and found three nitrogen oxide spikes, two of which correspond to well known supernovae: one event in 1006 AD and another in 1054 AD, which was the birth of the Crab Nebula (abstract). Both were widely reported by Chinese and Arabic astronomers at the time. The third spike is unexplained, but the team suggests it may have been caused by a supernova visible only from the southern hemisphere or one that was obscured by interstellar dust."
Re:The Crab Nebula wasn't born in 1054 AD (Score:4, Informative)
Re:Model A/B (Score:4, Informative)
If these really are the supernovae, doesn't this mean that "model B" is right and "model A" is wrong?
The two models look like extrema that bound the dates.
More interestingly, the sharpness of the spikes indicate that the sealing of atmospheric gases in the ice happens very suddenly. If it did not we would expect to see much broader and probably asymmetrical peaks.
This is consistent with, but does not absolutely prove, a rather prompt mechanism for such sealing, rather than the long lagtime process that is sometimes invoked to explain why temperatures always rise tens or hundreds of years before CO2 levels do in ice core data. It would be very peculiar, albeit not impossible, to have a process that sealed the ice tens or hundreds of years after it was laid down as snow, but did so on a timescale of a year or so.
Re:The Crab Nebula wasn't born in 1054 AD (Score:5, Informative)
It appears a nearby supernova could affect the climate, by ending it:
Dec 1, 2005 ... Is there a possibility that a nearby star could go supernova and destroy the earth? Or have other bad effects on us? ...
imagine.gsfc.nasa.gov/docs/ask_astro/answers/980521a.html
They said, in part:
If you are talking about the life on Earth, then there is a detailed calculation of the risks due to a nearby supernova on the web:
http://stupendous.rit.edu/richmond/answers/snrisks.txt [rit.edu]
The author concludes that a supernova has to be within 10 parsecs (30 light years) or so to be dangerous to life on Earth. This is because the atmosphere shields us from most dangerous radiations. Astronauts in orbit may be in danger if a supernova is within 1000 parsecs or so.
No stars currently within 20 parsecs will go supernova within the next few million years. ...
Re:The Crab Nebula wasn't born in 1054 AD (Score:5, Informative)
No. Assuming the resesarch is all legit & valid (I don't feel like carefully reading their methods right now), this still isn't relevant to Global Climate Change because this didn't affect climate.
You've got short term weather. Then you've got the average/trend of weather over very long periods of time, which is the climate. A 3 year (eyeballing it from the graph) spike in nitrogen oxide concentrations isn't considered climate. An effect on Earth, yes it appears that way, but not one that yields biological consequences. That burst vanished as quickly as it appeared. This sorta of stuff isn't even close to causing mass extinctions or new selection pressures.
Besides, the CO2 and other greenhouse gas emissions correlating pretty nicely with with the effects we're seeing, I'm not aware of any spikes in the temperature record that we need gamma ray bursts to explain.
Re:But there was no ice in the 1500's (Score:5, Informative)
You're citing an 1980 article from "Aramco World Magazine" to introduce a bunk story on par with lost-city-of-atlantis myths. It's not even a peer reviewed journal. It's a magazine. You're giving these Piri Reis maps much more credit than they deserve. You say they
closely resemble an ice-free Antarctica
but from what I just read the maps didn't even have a waterway between Antarctica and South America. An ice free antarctica should have a *huge* friggin' waterway there.
If these maps are correct, and there was no ice in the 1500's... how were these ice cores found?
They aren't correct. See above.
We have ice cores that we know go back more than 400,000 years. Give the guys who date these cores some credit. To me this iceless-antarctica idea just looks like a retired old historian/cartographer pushing a crackpot hypothesis. Yes, Antarctica wasn't always covered in ice, but that was millions of years ago.
Re:The Crab Nebula wasn't born in 1054 AD (Score:1, Informative)
RTFA, the only place the sentence quoted above is used is in the slashdot summary. The article correctly uses the words "witnessed" and "just 48 years later saw the birth of..."