This is a common question: what is the nearest star to the Earth that can explode as a supernova? Most people say Betelgeuse, a red supergiant in Orion, but there are several stars that are closer.
In the video below I answered this question as part of my weekly live video chat.
If you have an astronomy question you want answered, tune in to the live chat, which I usually do on Sundays at 15:00 Mountain time (21:00 UT). I might make a video of your Q&A!
Some notes: the image of Spica is used under the Creative Commons license, and is from fdecomite’s Flickr set. The awesome white dwarf illustration is from my friend the artist David Hardy (and PPARC), who gave me permission to use that in my book, so hopefully he won’t mind if I plug him here.
July 14th, 2008 at 9:36 pm
How far is the Sirius system? I thought that was a pretty close white dwarf/normal star pair.
July 14th, 2008 at 10:15 pm
I thought it was stars equal to or greater than 8 solar masses that go supernova…
“White dwarfs are incredibly dense…”
…like creationists…
July 14th, 2008 at 10:30 pm
Sirius A and Sirius B isn’t a contact-binary, wich is required to have a white dwarf explode into a 1a supernova, also Sirius B is estimated to be 120 million years old so my question is how long would it take for an average contact-binary white dwarf to explode into a 1a supernova?
Also for a normal supernova, the star does not run out of fuel, it has still plenty left, but the core of Iron just becomes to much and crosses the Chandrasekhar limit which results in a gravitational collapse, and there she blows as a galactic mr. Creosote.
July 14th, 2008 at 11:08 pm
I can’t get to Youtube at work but if one of the close ones she goes boom we’re stuck with the cheque, Monsieur yes? Pay the piper? Doomed?
Neat way of sterilising galactic regions though. Drake’s equation and all that.
July 14th, 2008 at 11:22 pm
A throughly enjoyable video! Now I can sleep at night. whew. My only complaint is this stupid ad they have for Madison Square Garden’s Dinosaur show…it kept “growling” over Phil’s lecture. grrrrrr myself.
July 14th, 2008 at 11:36 pm
Phil,
Thanks for answering my question in the chat. I read about GRB’s in Wikipedia, and when it said that one 4 light years away could incinerate the earth, I definitely paid attention… and lost a little sleep. Count me in for the book when it comes out.
Also, this is for the fray: Does anyone remember a gorgeous photo that Phil liked to, showing a huge hurricane from orbit? I’ve got back through the archives and can’t find it. A very striking photo.
c
July 15th, 2008 at 1:24 am
So speaking of that book.. when can I get my hands on it?
July 15th, 2008 at 1:26 am
@Nicole: Said
“White dwarfs are incredibly dense…”
…like creationists…
Well, I think it’s just wonderful that God put us in a place where we don’t have to worry. It’s just such a blessing that Satan can’t use any close stars and play with their nuclear fires and blow us up!
Phil:
When I was in High School, way back many years ago, before Pluto got Plutoids, our teachers would use the terms nova and supernova. Is there a difference? Are they 2 separate classes of exploding stars, and if so, what determines which?
July 15th, 2008 at 2:51 am
Michael L,
I also seem to recall a different naming convention. A “nova” was different from a “supernova”. A nova was supposed to result from an exploding surface of a white dwarf (Now called Type Ia supernova?) as opposed to a supernova (Now called Type II supernova?), which results from the core collapse of a giant star.
I have also heard the term “hypernova” which is supposed to be a supernova of stars far bigger than necessary to produce a black hole.
July 15th, 2008 at 3:13 am
Oh no!! Ejection! So, what are the chances of our minty little world suffering a similar ejectile fate?
July 15th, 2008 at 5:37 am
Tim G: novae and type Ia supernovae are two different phenomena: novae are the result of detonation of surface hydrogen/helium accreted onto a white dwarf, and the white dwarf typically survives – leading to recurrent novae. Type Ia supernovae are different and involve fusion of carbon in a white dwarf that approaches the Chandrasekhar limit (above which the white dwarf cannot be supported by electron degeneracy pressure). This destroys the white dwarf.
Out of interest, when Sirius A goes through its red giant stage, will the expansion be sufficient to start significant mass transfer to Sirius B? What about Procyon?
July 15th, 2008 at 6:16 am
Thanks, Andy.
July 15th, 2008 at 6:18 am
I laughed when you showed the white-dwarf-sucks-off-neighbors image… The colors were so similar to your objects that it was totally on target.
July 15th, 2008 at 6:38 am
Am I the only one that suspects that Phil could get his hands on plenty of nice little spheres and such for his models, but chooses slightly eccentric (astronomy joke!) ones on purpose? And are they going to get weirder?
“Let’s say that that yellow VW over there is our sun, and the Little Astronomer’s head is the Earth. Now, walk around the car in a circle, honey, and spin as you do so. And keep your head tilted 23 degrees. No,23 degrees. Good. Now, the sun has an axial tilt too, which we can simulate by flattening two of the tires…”
July 15th, 2008 at 6:48 am
OT: Pareidolia alert!
Today’s APOD (http://antwrp.gsfc.nasa.gov/apod/astropix.html) clearly shows The Face Of God (upper right) peering down on one of His creations, the Lagoon nebula. He was even nice enough to switch off all the stars so that we could better appreciate his handiwork.
July 15th, 2008 at 7:37 am
I stopped worrying about what a supernova would do to the earth when I saw a simulation of a black hole floating through the solar system. Now *that* is something worth irrational fear!
July 15th, 2008 at 7:59 am
Not to be too snarky, but there’s no specific time frame in the question. Given any amount of time, wouldn’t the answer be… Sol?
July 15th, 2008 at 8:03 am
Oh, poop. I just watched the video. Never mind.
July 15th, 2008 at 8:12 am
“It was ejected from my system.”
Phil, if you want the mint to be ejected from your system, you have to eat it first….
July 15th, 2008 at 8:35 am
Slightly OT, but I’ve written a piece of electronic music called “Pleiades” that I’ve decided to dedicate to Phil. Details on my website (click my name and select Music Catalogue), and if you want to download it, you can either get it from there, or from alt.binaries.sounds.mp3.avant-garde – share and enjoy!
July 15th, 2008 at 8:46 am
AH, Sol, destine to bloat and swell to a red giant stage,,,
Ah, the vicissitudes of old age,,,
GAry 7
July 15th, 2008 at 9:46 am
Phil,
Please write at least some of your response down in the future. My network nazis won’t let the videos play on my company’s network. So I still don’t know which star will be haunting my sleep tonight.
July 15th, 2008 at 10:45 am
Btw: Phil, Nice bookcover
Hopefully I can buy it here in “old Europe”, too… (maybe amazon must help…)
@Just Al: Nice idea
July 15th, 2008 at 10:49 am
Wait, we can prevent solar flares? We can prevent asteroid impacts?
With what technology? How are we even able to predict solar flares (we can’t) to prevent them (again, leaning towards no)?
July 15th, 2008 at 11:58 am
I’ll second the request for a transcript or summary for your video responses. YouTube and just about any video plays haltingly on my 1997 laptop, even on a decent connection. (Yes, I’d simply buy something newer if I could…)
July 15th, 2008 at 12:17 pm
Hmmm, a transcript is a good idea, and has been mentioned before. I can’t do that on my own, but maybe I’ll put a call out for an official BA transcriptionist. It’s not like I am print my own money, but I’ll have to think of something I can do for compensation. Suggestions?
July 15th, 2008 at 1:34 pm
A copy of your book?
July 15th, 2008 at 2:03 pm
I want that book so bad. Amazon.com says it comes out October 16th… arg, too far away. 3 months…
July 15th, 2008 at 2:30 pm
Here’s a transcript of the first quarter of the video. I don’t think the punctuation is perfect.
So, Phil Plait from BadAstronomy.com and I’m doing my live chat as I’m recording this and I was just asked: what is the nearest supernova candidate to the earth? Now a supernova is a star that explodes and there are two kinds. Stars like the sun cannot explode—they cannot explode…the sun will not explode—got it? Not! Everybody always says “The sun is going to explode!”—no! You need a much more massive star it has to be about twenty or more times the mass of the sun to explode. And after it lives its life out basically the core runs out of fuel and it collapses and it does two things. The outer layers of the star collapse down and they sort of rebound off the core—it sets off sort of a shock wave. Also because of very complicated physical processes neutrinos are created in the core and these are very ghostly particles. They can pass through light-years of lead without even seeing that it’s there but this incoming material gets a lot denser than lead and so it actually absorbs a lot of these neutrinos. A tremendous amount of energy is absorbed by that gas and when you dump a huge amount of energy into matter it basically explodes outwards and that blows the star up. And so that’s one way you can get a star that explodes.
July 15th, 2008 at 2:44 pm
Phil – My 81 year old mom wrote to me, (she reads your blog,) and about your talk she said: “Well, that’s a relief! Now I can go back to worrying about asteroids.”
July 15th, 2008 at 2:48 pm
Perhaps transcripts can be collaborative efforts. Videos can be broken down into more manageable parts.
July 15th, 2008 at 5:58 pm
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?
July 15th, 2008 at 11:01 pm
@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!
July 16th, 2008 at 2:18 am
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.
July 16th, 2008 at 10:44 am
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!
July 16th, 2008 at 11:25 am
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.
July 16th, 2008 at 6:09 pm
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?