If the distance to Betelgeuse is 430 light years, and if went supernova 430 yeas ago, would we be OK?

Question

Beteleguese, a red giant carbon star in Orion, is in the last phases of its life before going supernova. What would we see? Would it still be dark at night? Would we fry?

Answer 1

Good question. From what I have read there are two different types of supernovas: type 1 (like Betelgeuse) and type 2. And while both could potentially be dangerous type 2 are the far larger threat as they are far more numerous. According to wikipedia type 1 explosions release 10^44 joules whereas type 2 explosions emit 10^46 jules, 100 times more energy.

Stars large enough to go supernovae (type 1) are exceptionally rare in the cosmos and release only 1% of the estimated energy as type 2, although they can still be dangerous.

The bigger worry are type 2 supernovas, when a more massive white dwarf star is in a paired orbit with a larger star and it accretes enough matter to pass its Chandraskhar limit and kaboom. While these explosions aren't as large as type 1a, they are apparently more common and release 100x the energy of a type 1 meaning a greater danger to Earth.

At 430 light years we'd probably be okay with a type 1 supernova hitting us, with the exception of satellites and those who have to work outside during the flare up. A type 2 supernova...I'd rather not contemplate.

Answer 2

Liberal estimates predict it would be as bright or just slightly brighter than the full moon. Other estimates say more like the brightness of a crescent moon.

It would definitely shower us with cosmic rays and gamma rays, which could significantly deplete the ozone layer. It could also possibly trigger bright auroras for several months. We won't fry or go blind though.

One interesting historical fact is that a Chinese astronomer in the 1st century BC described Betelgeuse as white/yellow, but 200 years later, the Greek astronomer Ptolemy describes it as the familiar red we see today. The red giant phase is predicted to be 10's of thousands of years. If stellar evolution theory is correct, Betelgeuse shouldn't go supernova for thousands of years, if at all.

That would be cool though to have a dramatically visible supernova in our lifetime! Supernova 1987a was pretty disappointing.

Answer 3

First of all, Betelgeuse will not end up as a supernova. It is too smal to become that. It will end just as a standard nova. And if it was a nova, no, we wouldn't be effected. Of course we could see the nova (or supernova), but other than that, nothing would happen.
However, we (mankind) might not experience that. Betelgeuse is in the last satge of a star's life, yes, but it can still last longer than mankind will exist.

Answer 4

Actually there are so many different estimates of how close a supernova would have to be to Earth to do any damage that it's hard to give you a definite answer. One recent study says that the supernova would have to be within 50 light years to significantly harm life on Earth (http://www.abc.net.au/science/news/stories/s739717.htm) Another research group says that the star Eta Carinae, 7,500 light years away, could seriously harm our protective ozone layer (http://www.space.com/scienceastronomy/astronomy/milan_eta_carinae_000307.html)

Answer 5

I recall once computing how far we would have to be to a supernova to avoid dangerous levels of radiation. Unfortunately, I don't remember my answer, but it was pretty far. Maybe it was 100 light years that was dangerously close. Maaaaby as far as 430 light years would still be dangerous, but maybe not.

Answer 6

it seems that even if it did supernova it would not be a threat to life on earth.

look here:
http://en.wikipedia.org/wiki/Betelgeuse#The_Star.27s_Future

Answer 7

We'd all go blind