Close Supernova

[Tom Mazanec]

I have read SF books on Alpha Centauri or Sirius going supernova. How would this affect Earth?

[Nicolas]

People would look up.

Seriously, I don't know whether anything would change here. It still is several lightyears away, but supernovae are heavy stuff, so I really don't know.

[tofu]

I have read SF books on Alpha Centauri or Sirius going supernova. How would this affect Earth?

Why did they pick Alpha Centauri and Sirius?

Alpha Centauri is actually more than one star. The one that is currently closest to us is Proxima Centauri. It's really tiny, only 1/10 th the mass of the sun. The other two are pretty close to the sun's mass. Correct me if I'm wrong, but I believe that only giant stars go supernova. The centauri sisters will end their lives as red dwarfs. They'll go out with a whimper, not a bang.

Sirius also just happens to be a binary. The smaller one has already lived out its life and is, if I'm not mistaken, a dwarf. In other words, that star lived out its life and died without destroying our planet. The big one (Sirius A) is bright, but not particularly large, only 2 solar masses. So, I don't think it will go supernova either.

If you are looking for a star that really will go supernova, take a look at Betelgeuse, in the constellation of Orion. One day, it will blow up. That is an absolute certainty. It's far enough away though that there wont be any real negative affects to Earth. I mean, it wont kill us with radiation or anything. What it will do is light up the night sky brightly enough to read by for several weeks. After that, it will fade and eventually become invisible to the naked eye. At that point, a famous constellation that thousands of generations of humans have enjoyed, will be changed forever. I hope that I get to see it, so that I can tell my grandchildren that I remember what Orion looked like before he lost his shoulder. Pretty cool huh?

http://www.astro.uiuc.edu/~kaler/sow/betelgeuse.html

[ToSeek]

I have read SF books on Alpha Centauri or Sirius going supernova. How would this affect Earth?

According to this NASA article, any supernova within 25 light years or so would have devastating effects on life on Earth.

But, as tofu points out, there are no stars that close capable of going supernova.

[Nicolas]

By the time you see the supernova, it already happened years ago. Old news!! But it must be mighty impressive. "oh look if that happened here everything till past Pluto would be gone" "yeah it's a nice sight"

[Grogs1]

I'll take a crack at this. I pulled all of the hard numbers from my Astrophysics text, so hopefully they're close:

Energy flux=E/(4PI*R^2)

E would be the total energy released by the the supernova ~10^44 Joules.

R would be the distance from the star, so for Alhpa Centauri, R = 1.31pc = 4.04x10^16 meters.

The Energy flux would therefore be ~ 5x10^10 Joules per meter squared.

This figure happens to be very close to my calculation of the Energy flux produced by the sun in 1 year (~4x10^10 J/m^2)

The one variable I'm not certain of is the amount of time it takes the Supernova to release all of it's energy (seconds? weeks?) (Power = Energy per unit time) If it's anything less than a year (and I imagine it would be, at least for the majority of the energy,) we would be getting more power from the Supernova than from the sun, which would have to be devastating to the Earth.

[ngc3314]

I'll take a crack at this. I pulled all of the hard numbers from my Astrophysics text, so hopefully they're close:

Energy flux=E/(4PI*R^2)

E would be the total energy released by the the supernova ~10^44 Joules.

R would be the distance from the star, so for Alhpa Centauri, R = 1.31pc = 4.04x10^16 meters.

The Energy flux would therefore be ~ 5x10^10 Joules per meter squared.

This figure happens to be very close to my calculation of the Energy flux produced by the sun in 1 year (~4x10^10 J/m^2)

The one variable I'm not certain of is the amount of time it takes the Supernova to release all of it's energy (seconds? weeks?) (Power = Energy per unit time) If it's anything less than a year (and I imagine it would be, at least for the majority of the energy,) we would be getting more power from the Supernova than from the sun, which would have to be devastating to the Earth.

(I'm old enough to think in cgs...) The energy release in a typical supernovae is a few FOEs (FOE = ten to the Fifty-One Ergs). Of this, about 99% gos out in the neutrinos, dangerous only of you're close enough to be dead of something else. Of the remainder, about 99% goes into undoing the binding energy of the star (more if the star has stayed smaller and bluer like SN 1987A, less if it's a bloated supergiant). So figure the electromagnetic radiation output as some number times 10^(47) ergs, mostly released over a few weeks (say 1.5e8 seconds) for typical luminosity of a few times 10^39 erg/s. That comes in around a million solar luminosities.

If a collapsar is formed, don't stand on the axis. It will void your warranty.

But back o the original post - we now appreciate that Sirius and Alpha Centauri are quite safe from being supernovae. Now Betelgeuse, Antares, Eta Carinae - those are the ones to watch.

[TriangleMan]

This New Scientist article claims the safe distance is 160-200 light-years but for some reason 45-60 sticks out in my mind the safe distance limit.

[ChibiVader]

Correct me if I'm wrong, but I believe that only giant stars go supernova.

It takes a star with at least 8 solar masses during its main sequence lifetime to become a supernova.

[Tobin Dax]

http://www.astro.uiuc.edu/~kaler/sow/betelgeuse.html

8)

[shameless plug] If you're really interested, check out Jim's pages on Alpha Cen and Sirius, and that will help to show that they won't explode in a supernova.[/shameless plug ]

[Tom Mazanec]

The Sirius book handwaved (and leg kicked) aType I out of the binary. The characters in the Alpha Centauri books (|I think there were two books) KNEW that Alpha Cent could NOT go supernova. But it did anyway. Why was a good part of the second book, so I won't go into it.

[Jobe]

By the time you see the supernova, it already happened years ago. Old news!! But it must be mighty impressive. "oh look if that happened here everything till past Pluto would be gone" "yeah it's a nice sight"

lol.

Already happened where? Remember there is no absolute time : p

[Tobin Dax]

The Sirius book handwaved (and leg kicked) aType I out of the binary. The characters in the Alpha Centauri books (|I think there were two books) KNEW that Alpha Cent could NOT go supernova. But it did anyway. Why was a good part of the second book, so I won't go into it.

Now that I think about it, JMS has our sun go Supernova in about 1 million years in the Babylon 5 universe. His method is a little off, but tweakable. Oh, yeah, this would *really* affect Earth.

[tofu]

Now that I think about it, JMS has our sun go Supernova in about 1 million years in the Babylon 5 universe. His method is a little off, but tweakable. Oh, yeah, this would *really* affect Earth.

What's his method? I don't think there's any possible way to make our sun go supernova. Maybe I've wrong.

[frenat]

The Sirius book handwaved (and leg kicked) aType I out of the binary. The characters in the Alpha Centauri books (|I think there were two books) KNEW that Alpha Cent could NOT go supernova. But it did anyway. Why was a good part of the second book, so I won't go into it.

What are the titles and authors of these books?

[Eroica]

Sirius B is a White Dwarf. Is there any possibility it could ever acquire enough matter from Sirius A to produce a Type I Supernova?

[Kaptain K]

Sirius B is a White Dwarf. Is there any possibility it could ever acquire enough matter from Sirius A to produce a Type I Supernova?

No! The seperation is too great for it to siphon off material. The dwarf must be in a "tight" orbit in order for that to happen.

[Ilya]

The characters in the Alpha Centauri books KNEW that Alpha Cent could NOT go supernova. But it did anyway. Why was a good part of the second book, so I won't go into it.

What are the titles and authors of these books?

"Aftermath" and "Starfire" by Charles Sheffield.

[Tobin Dax]

Now that I think about it, JMS has our sun go Supernova in about 1 million years in the Babylon 5 universe. His method is a little off, but tweakable. Oh, yeah, this would *really* affect Earth.

What's his method? I don't think there's any possible way to make our sun go supernova. Maybe I've wrong.

IIRC, he suggested that there is a jumpgate that opened into the sun and drained some of it's mass. (I'm paraphrasing here, and I should add that this was never established on the show, so it isn't necessary canon, at least not yet.) I don't know why he thinks that a star losing mass rapidly would cause a supernova (*I* don't recall that it would, if that means anything). After a little thought, I would dump some silicon plasma or something, probably from a near-SN O/B star, which hopefully wouldn't cool significantly in a day. Unfortunately, this won't work for JMS either, as humans had enough warning from Sol that something funky was up.

[ZaphodBeeblebrox]

Now that I think about it, JMS has our sun go Supernova in about 1 million years in the Babylon 5 universe. His method is a little off, but tweakable. Oh, yeah, this would *really* affect Earth.

What's his method? I don't think there's any possible way to make our sun go supernova. Maybe I've wrong.

IIRC, he suggested that there is a jumpgate that opened into the sun and drained some of it's mass. (I'm paraphrasing here, and I should add that this was never established on the show, so it isn't necessary canon, at least not yet.) I don't know why he thinks that a star losing mass rapidly would cause a supernova (*I* don't recall that it would, if that means anything). After a little thought, I would dump some silicon plasma or something, probably from a near-SN O/B star, which hopefully wouldn't cool significantly in a day. Unfortunately, this won't work for JMS either, as humans had enough warning from Sol that something funky was up.

It wouldn't cause a Supernova, per se ...

What it would do, however, is cause a Massive Infall of gas, into the Sun.

This in turn, would Rebound, off of what was Left, of the Core.

If Violent enough, this could very well, Mimic a Supernova Explosion.

[JonnyWishbone]

Given that humans are encounter-suit wearing Vorlon-like beings who can flip-flop between matter and energy states when the nova of Sol is mentioned in "The Deconstruction of Falling Stars," I'd always assumed it was the result of some crazy super-weapon like the Shadows and Vorlons used to cart around. Or those pesky fellows from Thirdspace.

Cheers, Jon

[Tom Mazanec]

Author Name: Allen, Roger Macbride; Kotani, Eric

Title: Supernova

Is the Sirius book.

[umop ap!sdn]

Sirius also just happens to be a binary. The smaller one has already lived out its life and is, if I'm not mistaken, a dwarf. In other words, that star lived out its life and died without destroying our planet.

Don't forget about proper motion. [-X Sirius was probably much farther away from us when that happened. I'm not sure though how likely it is that any star ever did explode while it was that close to us. :-k

[eburacum45]

An essay by Michael Richmond;

Will a Nearby Supernova Endanger Life on Earth?
http://stupendous.rit.edu/richmond/answers/snrisks.txt

There is some evidence for a relatively nearby supernova explosion 2.8 million years ago;
http://www.astro.uiuc.edu/~bdfields/NearbySN.html

the extinction that occured then was not one of the worst that has happened on our little planet.
I think supernovae occur nearby (say within a couple of hundred lightyears) relatively frequently; like medium sized meteor impacts, they seem to have little impact on the biosphere.

[Eroica]

Don't forget about proper motion. [-X Sirius was probably much farther away from us when that happened.

But when did that happen? 100,000 years ago, Sirius was probably only about half a light-year further away than it is today.

Anyway, Sirius B only went through a red giant phase before becoming a white dwarf. That wouldn't endanger Earth unless it happened within a few AUs!