what is the distance at which the explosion of a supernova could wipe out all life on earth ?
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.
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
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?
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
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. ..
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?
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?
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:
And too many others to count.
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:
Authors: Roger MacBride Allen and Eric Kotani
Published by: Avon books
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.
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."
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
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.
Would there be any gravitational effects that might cause earthquakes?
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.
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 http://www.sas.upenn.edu/~esteig/data/betd.dat [Broken] 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.
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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