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Supernova could wipe out all life on earth ?

  1. Mar 23, 2004 #1
    what is the distance at which the explosion of a supernova could wipe out all life on earth ?
  2. jcsd
  3. Mar 23, 2004 #2


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    Current thinking generally puts the distance at about 25 light-years. At this distance, the gammaray bursts could strip the ozone layer from the earth, leaving the entire surface to be bombarded by solar radiation and sterilized.
  4. Mar 23, 2004 #3


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    what about ocean life forms
    wouldnt living beneath a layer of water protect them
    and what about nocturnal land-animals who live on fish

    it just so happens that I sleep days and eat nothing but
    smoked salmon and suchi
    so I assume I would be all right
    please tell me if I am deluding myself, Lurch, I dont
    want to be living in a fools paradise
  5. Mar 23, 2004 #4
    Are there any candidates for supernovae anywhere around us? I hear that Beatle Juice is a red giant ready to do supernova. I also hear that Sirius (the dog star) has a strange history. Are there any candidates close enough not to wipe out all life but create, say, a world wide devastating earthquake?

  6. Mar 23, 2004 #5

    This page says that Sirius B will not likely undergo type IA supernova

    Betelgeuse will go supernova, but is 600 ly away

    The next star in our galaxy that is believed that will explode in supernova is Rho Cassiopeia, but luckily, is 10000 ly away
    Last edited: Mar 23, 2004
  7. Mar 24, 2004 #6


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    Your posts, writings and links have always been helpful, but I have a terrible urge to blast the "Ask Astronomer" (certainly not you) who wrote that little link you gave. He is right about masses and distances of the Sirius system, but his info on what will and will not go supernova is so incomplete and flat-out wrong that anyone new to the subject would learn either nothing or learn it wrong.

    Type I and Ia supernovae (Binary systems) have been discussed in detail several times on this forun and I would urge any reader to search back for some of the longer threads on PF for this subject. Please read this fast before Janus deletes it for being argumentative instead of informative. ..
  8. Mar 24, 2004 #7
    Perhaps you could give a summary of the conclusions of what will go supernova or not. That would be informative. Or perhaps you can find the thread you are talking about and give a link. Thanks.

    I've often wondered if it were possible for a white dwarf or nuetron start to be so cool that we cannot detect it nearby. And could such a star be right on the edge so that if it passes through a dust cloud, it could accumulate enough mass to blow?
  9. Mar 24, 2004 #8
    Does the Sirius system have any gas giants that orbit that system?

    Could we detect a gas giant headed for Sirius B if there were?
  10. Mar 24, 2004 #9


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    Here is just one post: https://www.physicsforums.com/showthread.php?s=&threadid=8073&highlight=labguy
    of several that went into even more detail in other posts:

    Originally posted by Ambitwistor
    Thanks. I was hedging: I thought I remembered reading that some type I (not Ia) supernovae could undergo gravitational collapse (do you know if this is true?), so I thought there might be something left over.

    They all undergo gravitational collapse; this is where the "initiating" energy comes from.

    But, in the case of a Type Ia supernova, a very small percentage of accreting white dwarfs will become type Ia's. The "chemical conditions" of the Dwarf are specific and rather rare. The Dwarf must be composed mainly of Carbon and Oxygen (sometimes Si). Also, the mass limit for the supernova is ~1.38 - 1.39 Solar masses, not the "standard" 1.44 Chandra's limit. The Carbon is the catalyst, and it must detonate or burn (deflagration) at a specific rate to cause the energies required for the total fusion of all material into the heavier elements, leaving no core remnant at all.

    This was discussed at length (I think) in an older thread several months ago. S. E. Woosley is considered the foremost "expert" on Type Ia supernova since he has spent his entire career on the subject, and there are still uncertainties about which carbon "detonation-deflagration" models are most likely. Quite a bit about these can be found at:


    Click on "Introduction" first.

    Some "outside" links on what will and will not become supernova are:
    http://astronomy.nju.edu.cn/astron/AT3/AT32103.HTM#Anchor-Type I supernovae

    And too many others to count.
    Last edited: Mar 24, 2004
  11. Mar 24, 2004 #10
    There's a fiction novel entitled "Supernova" in which Sirius B blows up. The gamma ray burst acts like an EMP and wipes out half the globe's electronics (and thus civilization). I'm not sure how scientifically accurate this effect is, but the book was co-authored by an astrophysicist, giving it some bit of logos. I remember some religious end-of-the-world type cults played a big part in the novel too. It's not a bad read:

    Title: Supernova
    Authors: Roger MacBride Allen and Eric Kotani
    Year: 1991
    Published by: Avon books
  12. Mar 24, 2004 #11


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    There are, IMHO, two ways we could approach the question of 'potential supernovae that will wipe out multi-cellular life* of Earth':
    1) what stars are presently within ~25 ly?
    2) what stars might be within ~25 ly in the next 500 million years?

    As Labguy has mentioned, SN may happen to a) very massive stars or b) through accretion onto certain white dwarfs.

    In the first case (a), are there any sufficiently massive stars nearby, even assuming binaries magically merge? No

    In the second case (b), are there white dwarfs which *could* accrete the right stuff and go SN? How about stars which aren't white dwarfs now, but could be in future? One way to get an upper bound on this is to ask "how many stellar systems, within 25 ly, have a combined mass of >1.38 sol (or whatever the minimum is for a white dwarf to go SN)?" Answer: ...??

    Much more interesting is 2)! Anyone want to take a stab at an approach we could use to get an answer?

    *OK, there's a good discussion to be had about whether ecosystems around deep-sea vents would be affected by anything but the closest of SN. Not to mention that bacteria 10km down in solid rock would remain blissfully ignorant - if they are conscious - of any such SN.
  13. Mar 25, 2004 #12


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    NEREID, this is an old paper 1995, it topic is mass extinctions
    due to SN, it does not mention sea life, but it may be
    from a post in biology.

    "D. radiodurans (as the specific epithet suggests) is withoug doubt the most radiation-resistant organism known on the planet. A pinkish bacterium that smells vaguely of rotten cabbage, it was isolated originally from canned meat that had spoiled despite being irradiated (it has turned up in irradiated fish and duck meat, as well as in the dung of elephants and Ilamas and in granite from Antartica) (Travis 1998). It grows happily in radioactive waste sites in the presence of levels as high as 1.5 million rads (keep in mind that's over 1,000 times the 1,000 rads that kill humans and sterilizes American cockroaches). In a frozen state it may even be able to withstand 3 million rads."
    Last edited: Mar 25, 2004
  14. Mar 26, 2004 #13

    How do you come to that 25 ly ? Can you calculate that distance or did you come to that figure by observation of existing supernovae and their effects.
    Another question : how can galaxies collide as they move away one from another because of the expanding universe
  15. Mar 26, 2004 #14


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    Welcome to Physics Forums picass!

    I've not seen the paper which concluded 25 ly (maybe LURCH can give us a link), or if I did read it, it was so long ago that I've forgotten. However, the idea is roughly as follows:
    - we know how much energy a supernova (SN) produces, across the whole electromagnetic spectrum and in neutrinos and motion of remaining nuclei and electrons
    - we can therefore work out what would hit the Earth's atmosphere, for a SN at distance x ly
    - we can model the effects on the atmosphere
    - when we do that, we see that 'complex life' would be wiped out, if the SN were at a distance of ~25 ly.

    What would be the principal cause of death? I don't know what the models say, but my guess is ionising radiation, due to high energy particles generated in the atmosphere by both the intense gamma radiation and the 'cosmic rays' from the SN; kinda like a billion solar flares all at once.

    If we could survive the radiation, maybe the chemistry of the atmosphere would be so changed as to kill us? or the climate altered dramatically??

    Instead of looking up a paper, why don't we take a stab at doing the calculations ourselves?

    Galaxy collisions? Leaving aside the possibility of the Big Rip, galaxies (and inter-galactic gas, and dark matter, and ...) in clusters and super-clusters do not move apart from each other due to the expansion of the universe because their mutual gravity is stronger. Within the cluster and super-cluster, galaxies (etc) move in more or less chaotic orbits about the centre of mass of the cluster (this is oversimplifying things a bit), and so will inevitably collide every now and then.
  16. Mar 26, 2004 #15
    Would there be any gravitational effects that might cause earthquakes?
  17. Mar 26, 2004 #16


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    Take this in two steps: does Proxima Centauri (or Alpha Cen, or ...) - a nearby star, at a distance of ~4ly - have any observable gravitational effect on the Earth? No. So whether or not a star is at a place 25ly from us makes no gravitational difference.

    Next, a SN is a very large (space) change in the distribution of an awful lot of mass in a very short period of time. Could that cause a sharp 'spike' of 'gravitational radiation'? Yes! Could that be detected by LIGO or LISA? Yes! Could that spike cause earthquakes? Very unlikely.
  18. Mar 28, 2004 #17
    Nevertheless, it's interesting to see if we can tie previous extinctions to super-novaes as I was searching for the demise of the megafauna (Mammoths) at the end of the ice age (11,670 years ago)

    We came up with this:

    A striking coincidence, isn't it?
    However, as it was assumed that the radioactivity would translate to spikes in cosmogenic 10Be, 14C, 37Cl etc we searched several datasets, to come up with a very distinct spike of 10Be concentrations of Tayler Dome ice core at 14.980 years BP but nothing at 11,400 or younger.

    All in all we have found not much evidence for that possibilitly that radioactivity killed the Mammoths and the other megabeasts. Right now we think it was the clathrate gun (Kennett et al) that killed them.
    Last edited: Mar 28, 2004
  19. Mar 28, 2004 #18


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    The conspicuous infrequency of supernovi in the Milky Way gallaxy is also a significant factor to put into the Drake Equation. Most other gallaxies experience far more SN than we do, so the chances of life arrising on a planet in any given location is decreased by the increased probability of a supernova near that location.
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