Comments on: What is the nearest star to Earth that can go supernova?

By: amphiox

amphiox — Thu, 17 Jul 2008 00:09:53 +0000

Question 1: What would it look like if Spica or any of the other close (inside 500ly, say) stars went supernova? Are we talking brighter than full moon here? Could it be possible to be brighter than daytime sun? How useful would such an event be for astronomers, compared to more distant supernovae?

Question 2: White dwarfs last for very long periods of time, right, as in trillions of years? Given long enough periods of time, would it at all be possible for Sol to become a contact binary, ie by being captured/capturing another star on a random close approach?

By: AJWM

AJWM — Wed, 16 Jul 2008 17:25:22 +0000

A variation on the question: what’s the nearest star (or stars) that might go supernova anytime soon, like within the next couple of thousand years? Anything nearby (for sub kiloparsec values of “nearby”)?

What about hypernovas? I know Eta Carinae underwent a “false supernova” event circa 1843, and is expected to blow Real Soon Now, but that’s something over 7500 ly away. Anything else whose size/distance value gives an equivalent (or greater) threat? Thanks.

By: Ryan Jensen

Ryan Jensen — Wed, 16 Jul 2008 16:44:00 +0000

Would it be possible, on these video answer blog posts, to add a transcript or at least the answer to the post? I am at work and cannot watch videos (the sound goes through the whole restaurant).

Thanks!

By: Phil Plait

Phil Plait — Wed, 16 Jul 2008 08:18:20 +0000

Bynaus, I was simplifying in the video. But it’s more complicated than you say as well; there are many kinds of Type I events. As another example, a helium-capped CO white dwarf can detonate with a subsonic wave of fusion over its surface, and triggered by the event the star itself completely explodes.

By: Bynaus

Bynaus — Wed, 16 Jul 2008 05:01:38 +0000

@Phil: Thank you for this blog entry, BUT… Supernovae Type Ia (the white dwarf thing) happen when the white dwarf accumulates enough mass to cross the Chandrasekhar-limit, which is about ~1.4 solar masses: only then the white dwarf will collapse under its own mass (finally overcoming electron degeneracy pressure) and/or ignite the carbon-fusion at its center and explode.

The accumulation of unburnt hydrogen stolen from the red giant companion and the subsequent thermonuclear reactions on the surface of the white dwarf exist though: they are called nova events: very bright, but no supernova, no big explosion that destroys the star.

But the ashes of these events (the fusion products) accumulate on the surface and, over time, steadily push the white dwarf a little further towards the ~1.4 solar masses limit mentioned above.

So it’s nova-nova-nova-… …-nova-SUPERNOVA!

By: Valdis Kletnieks

Valdis Kletnieks — Tue, 15 Jul 2008 23:58:14 +0000

OK, now here’s a slightly different question – I’ve seen *lots* of stuff on the web that talk in great detail about what happens to the white dwarf partner in the binary system when it goes Type Ia Supernova.

But I haven’t found *anything* about what the likely fate of the *other* star is…

Anybody got a pointer on that one?

By: Tim G

Tim G — Tue, 15 Jul 2008 20:48:40 +0000

Perhaps transcripts can be collaborative efforts. Videos can be broken down into more manageable parts.