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Effective Destructive Range of Supernovae?

  1. May 9, 2009 #1
    Hey all,

    It’s been a while since I’ve visited the forums but my question is strangely one that I’ve had a difficult time trying to find an answer for.
    I was wondering if anyone either knows or can point me to information regarding the effective destruction radius of a supernova, preferably for Type 1a. By destruction radius I mean the distance in light years that the supernova shockwave could either cause irreversible destruction on the terrestrial planets within a star system or destroy the ozone of a system's planets to the point that they could no longer protect all but the most hardy microbial life.

    Specifically, I’m looking for the range within a galaxy that a supernova would pose a mass extinction event to animal life. I’ve heard that some Type 1a Supernova can be a potential threat to humans within a range as large as 3300 LY. However, the terms of threat to humans were somewhat vague in all the sources I’ve read. I don’t care what range a supernova may potentially induce cancer or interfere with circadian rhythm. I want to know how close a system must be to have complex life eradicated either directly from the blast of the shockwave or by means of stripping the ozone to lethal levels.

    I was also hoping I could get some clarification regarding the velocity of a supernova shockwave. I’ve read that the shockwave can expand anywhere from 1-10% c. I thought that Type 1a supernova always went nova at 1.4 solar masses so shouldn’t this number be in a fairly well defined range?

    Any information would be greatly appreciated. I wish I could say this information was going to be used for some noble cause, but alas, I’m just an amateur sci-fi writer that needs some help.
     
  2. jcsd
  3. May 10, 2009 #2

    Chronos

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    A supernovae within 30 light years could threaten life on earth. A GRB, on the other hand, could be perilous out to about 2000 light years - perhaps further if pointed in the wrong direction. Fortunately, no such serious candidates exist in our neighborhood. The Sirius system is perhaps the most threatening. Sirius is a blue giant with a white dwarf companion located only several light years away from earth. It does not, however, appear to be a threat at this time [no evidence of gas stripping]. When Sirius A reaches its red giant phase, the game may change. We still have a considerably many millions of years to ponder a defense. Eta Carinae is another suspect. But at 8000 light years, it is probably too distant to be much of a concern. See http://www.space.com/scienceastronomy/astronomy/gammaray_bursts_010522-2.html [Broken]
     
    Last edited by a moderator: May 4, 2017
  4. May 10, 2009 #3
    Thanks for your response.

    That seems like a much smaller range than I was expecting. Since I'm applying this information in a fictional setting I'm not too concerned with potential supernova candidates in regards to Earth. In fact, general information concerning the effects of a supernova as it applies in a hypothetical region of the galaxy would be most useful. It’s still interesting to know that there is a potential super nova candidate several thousand light years away.

    Do GRB’s actually occur in the Milky Way or other spiral galaxies? I thought they were all thought to be extragalactic events that occurred in newly forming galaxies. I had actually considered using a GRB in my fiction but the fact that they are estimated to only occur every 100,000 to 1,000,000 years per galaxy makes the prospect of them occurring near a life-inhabited region of the galaxy very improbable despite their large range. Since supernovae occur about every 50-100 years per galaxy it seemed that their threat to an inhabited region of the galaxy is more likely even if they are relatively rare on civilization time scales.

    I’ve also read that some scientists believe a supernova may have been responsible for the Ordovician Mass Extinction approximately 450 million years ago. Are there any theories to how close this supernova would have been to Earth?
     
  5. May 10, 2009 #4

    Chronos

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    If the ordovician extinction event was caused by an exploding star, it most likely was a GRB. A GRB, if beamed directly at earth could be destructive out to around the distance of Eta Carinae [which does not appear to be pointed our direction]. A garden variety supernova must be much closer to have such an impact, and no qualifying supernova remnants have yet been detected.
     
  6. Jun 16, 2009 #5
    In the book "Death From The Skies" from Phillip Plait, he spends endless chapters discussing the exact questions you posed in this thread.

    https://www.amazon.com/Death-Skies-These-Ways-World/dp/0670019976

    The answers above are probably enough to satisfy your fiction-writing research, but if you want to know a bit more about all the destructive ranges of gamma ray bursts, supernovae, quasars, neutron star magnetic fields, and more, check the book out. It's an entertaining read.
     
    Last edited by a moderator: May 4, 2017
  7. Jun 17, 2009 #6

    Chronos

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    All GRB events observed to date have occured at great distances from our galaxy. Hence, it is probable any are unlikey to occur in our neighborhood. A popular theoiry is they are extremely metal deficient and massive stars. According to current theory, no 1a candidates are known to exist near enough to earth to pose an immediate threat. You need a binary system consisting of a red giant with a nearby white dwarf companion to qualify for such an event
     
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