Betelgeuse! Betelgeuse! Betel-- BOOM!

[tdvance]

at 20 solar masses, it would be a sure thing that it becomes a black hole (according to a book I have from about 1990 or so--we might know better now).

But, that doesn't mean much of it would fall back--strong in the force is gravity...but not that strong (unless you are really close to the event horizon).

Since it is gravitational energy that fuels the supernova outburst (the collapse of the core turns lots of potential energy, and matter, into kinetic energy, including radiation), I'd think a star becoming a black hole would be a brighter supernova than one becoming only a neutron star.

[Don Alexander]

OK so when the big B does go there is a possibility that it could develop into a black hole. If a black hole did occur, how much of a light show would we really see? The initial explosion would push much of the material away , but I would think that much of it would fall back in because of the gravitational effect. Instead of a huge light show we would only see something the brightness of a nova.

You might want to read up on how supernovae actually work...

Now, as I mentioned before, there are theories that predict failed supernovae - check out this paper for more details on that. In such a case, the star would spiral into the black hole with also no explosive signal.

On the other hand, the best understanding of gamma-ray bursts we have today tells us that massive stars can explode, producing a black hole and a very powerful supernova at the same time.

Once the supernova explosion is actually launched (a process that obviously occurs but is still not really understood), there is no stopping the expansion.

Remember, black holes do not increase gravity!! If you have three solar masses within a radius x, this will have an (assuredly strong) surface gravity - if you collapse those three solar masses into a black hole the gravity at radius x remains unchanged!! Any matter that reaches escape velocity from three solar masses at radius x will escape from the black hole just as readily as from an uncollapsed core.

[Fiery Phoenix]

I think they really mean that the explosion is about to reach us, indicating that it has already occurred. Either way, I would absolutely love to witness the event.

On a related note, I feel curious to see what Orion would look after the explosion of Betelgeuse.

[chornedsnorkack]

Once the supernova explosion is actually launched (a process that obviously occurs but is still not really understood), there is no stopping the expansion.

Remember, black holes do not increase gravity!! If you have three solar masses within a radius x, this will have an (assuredly strong) surface gravity - if you collapse those three solar masses into a black hole the gravity at radius x remains unchanged!! Any matter that reaches escape velocity from three solar masses at radius x will escape from the black hole just as readily as from an uncollapsed core.

Overcome gravity yes, but accelerate?

Once the core has collapsed AND produced an explosion, the bulk of the star is still there, all around the core and the explosion. The explosion must somehow accelerate it as well.

If the core turned into a neutron star, the neutron star will support pressure by its great stiffness and it is immensely hot, assuring huge pressure of gamma rays all between the neutron star and the explosion, which keeps accelerating the explosion. The matter density between the neutron star and explosion may be low, but pressure of the radiation and the little matter is very high.

However, if a black hole were to form, it would support no pressure and emit no heat. The event horizon would be the path of least resistance for the contents of the interior of the star, so as the driving pressure is released from behind, the explosion should weaken and eventually stop and fall back into the hole...

[Don Alexander]

Basically, this is a good point, and since supernovae are still not "exploding in the lab", I don't think anyone can truly answer that.

But one thing you seem to be forgetting is angular momentum. The matter doesn't just fall into the star, it's going to form a viscous accretion disk in the equatorial plane, and it must remove angular momentum to actually cross the event horizon. This is done by drag (thus, a viscuous accretion disk), which heats the disc up to MK temperatures, releasng copious amounts of radiation. This may then power the outward acceleration of most of the star's shell.

[rommel543]

You might want to read up on how supernovae actually work...

Now, as I mentioned before, there are theories that predict failed supernovae - check out this paper for more details on that. In such a case, the star would spiral into the black hole with also no explosive signal.

On the other hand, the best understanding of gamma-ray bursts we have today tells us that massive stars can explode, producing a black hole and a very powerful supernova at the same time.

Once the supernova explosion is actually launched (a process that obviously occurs but is still not really understood), there is no stopping the expansion.

Remember, black holes do not increase gravity!! If you have three solar masses within a radius x, this will have an (assuredly strong) surface gravity - if you collapse those three solar masses into a black hole the gravity at radius x remains unchanged!! Any matter that reaches escape velocity from three solar masses at radius x will escape from the black hole just as readily as from an uncollapsed core.

So reading the paper (which gave me a headache because of all the antiquated citations) there is a possibility that a star can turn into a BH without going nova just not a decreased nova. It's boom or no boom.

So what would happen if Eta Carinae transitioned directly into a a spinning BH. I know it's been stated that the gravitational influence doesn't change when the star collapses but would the increase spin cause the surrounding nebula to either be blown away or pulled into the accretion disk? What is the reach of the frame dragging caused by the spinning?

[Dgennero]

It says in the Berkeley release that the shrinking (of Betelgeuse) is smooth but accelerating.
This needs to be watched (how many data points do we have from the past btw.?) closely so that we can get a graph.
We could then extrapolate (or, if the graph closely resembles a known function, use calculus) to see when the diameter would become critically small - small enough for a violent rebound (supernova).
Does anybody know if the "rebound-diameter", which should be a function of stellar mass, is known?
I hope Betelgeuse does us the favor, it would be the first close supernova-event in the space age and provide a wealth of data - and we'd see it *as it develops*, not when it is already happening, which means it would be easier for us to predict such an event in the future.
My favorite runner-up is the semiregular mu Cephei, this one and maybe a handfull others within 1-2 kpc also need watching.

[Fiery Phoenix]

^ Something tells me it's going to blow up in our lifetime and we'll get to witness it ourselves. Just how awesome would that be? And, of course, how lucky we would be!

[antoniseb]

Does anybody know if the "rebound-diameter", which should be a function of stellar mass, is known?...

I don't know the answer here, but I can tell you that what we are looking at is the photosphere, which is huge and sparse. I believe that if you were to calculate the density of the gas in that outer part of the star, it would be a better vacuum than we can make on Earth. This diameter shrinking 15% is not something that will result in some kind of rebound. It is compression deep within that we will never see with photons that is important.

[Ampatent]

Am I the only one that is distraught over the pronunciation of Betelgeuse? Beetle juice just sounds so weird... I'd much rather say beetle guys.

[Fiery Phoenix]

Am I the only one that is distraught over the pronunciation of Betelgeuse? Beetle juice just sounds so weird... I'd much rather say beetle guys.

Pronunciation is one of the most tentative things in astronomy as a whole anyway. I think it would be a wise thing if the IAU devote some time for this particular issue and see what they can do about it. Lots of people just pronounce stars and moons' names the way they want, which, if you think about it, can actually lead to undesired consequences at times.

[Dgennero]

...especially if you are talking about sending a probe into Uranus
For this one, I adopted the pronunciation "you ran us" as suggested somewhere way back in another thread.
Betelgeuse can be pronounced "bettl-juice", which Merriam Webster has as an option and I also found it in this pronunciation guide: http://www.wsanford.com/~wsanford/ex...ion_guide.html
In my native Germany there is an alternative spelling "Beteigeuze" with the pronunciation "bay-tie-GOY-tsuh", and the French probably say "bettl-ZHIRS".
By the time the English pronunciation is finally settled, we'll probably have no more reason to argue about it

[Fiery Phoenix]

It's not just Betelgeuse, though. Tens of other celestial objects have names that are tentatively pronounced. Take Saturn's moons as an example, such as Iapetus, Rhea, etc. Moreover, I've met people who don't know how to pronounce Rigel.

The only remedy for this is to decide on a single, settled pronunciation for these words, and I think that would be the IAU's job.

[Buttercup]

Everytime I see this thread, I laugh. --BOOM! Lol!

[tdvance]

Am I the only one that is distraught over the pronunciation of Betelgeuse? Beetle juice just sounds so weird... I'd much rather say beetle guys.

As I said in the "geek argument" thread, it's Bet - el - Juice, and nothing else!!!

[Buttercup]

Beatle Juice. It's what The Fab Four had every morning with bacon and eggs.

[Jens]

The only remedy for this is to decide on a single, settled pronunciation for these words, and I think that would be the IAU's job.

This is a question I sometimes ask, but do you mean the proper pronunciation in English, or in general, i.e. in all languages? If you mean the latter, you will run into difficulties, because just taking Rigel, there are many languages in the world that have no "r" sound, and there are also many languages where it is not permitted to end a word with a consonant (many Polynesian languages are like this). So I just checked on Wikipedia, so I might be wrong, but apparently the correct pronunciation in English is something like "Raijel," where in Japanese the correct pronunciation is "Riggeru." Are you suggesting making an ideal pronunciation in International Phonetic Alphabet, and then saying that local languages should adopt it to their phonology? Or are you just saying that the IAU should set the pronunciation in English?

And not in response to this comment, but I really like the name Betelgeuse. In fact, I really like the names of most stars that derive from Arabic. There's something exotic about names like Aldebaran and Rigel.

[Fiery Phoenix]

This is a question I sometimes ask, but do you mean the proper pronunciation in English, or in general, i.e. in all languages? If you mean the latter, you will run into difficulties, because just taking Rigel, there are many languages in the world that have no "r" sound, and there are also many languages where it is not permitted to end a word with a consonant (many Polynesian languages are like this). So I just checked on Wikipedia, so I might be wrong, but apparently the correct pronunciation in English is something like "Raijel," where in Japanese the correct pronunciation is "Riggeru." Are you suggesting making an ideal pronunciation in International Phonetic Alphabet, and then saying that local languages should adopt it to their phonology? Or are you just saying that the IAU should set the pronunciation in English?

And not in response to this comment, but I really like the name Betelgeuse. In fact, I really like the names of most stars that derive from Arabic. There's something exotic about names like Aldebaran and Rigel.

The former. But that's only because of the fact that English is the number one language in the world right now. I'm sure the IAU could do it if they wanted.

[Ampatent]

And not in response to this comment, but I really like the name Betelgeuse. In fact, I really like the names of most stars that derive from Arabic. There's something exotic about names like Aldebaran and Rigel.

I don't really have a problem with the name, it's just the pronunciation that irks me. Every time I hear it I think of that movie from the 80's.

[H4wkeye]

I think they really mean that the explosion is about to reach us, indicating that it has already occurred. Either way, I would absolutely love to witness the event.

On a related note, I feel curious to see what Orion would look after the explosion of Betelgeuse.

Wait.So if it already occurred,how come no telescope or w/e spotted it yet?Cuz of the distance that light has to travel or?

[Tog]

Wait.So if it already occurred,how come no telescope or w/e spotted it yet?Cuz of the distance that light has to travel or?

Yup.

You ever see a live fireworks display? You'll see the flash from one of them, then about a quarter second later, you hear the "boom". Sound takes time to get to you. So does light. We are around 620 light years from the star. That means that we see it as it existed 620 years ago. A telescope won't change that, but it will let us see it in more detail (if it's really big). What we see won't change, only the way we see it.

Because of the distance, it could have exploded 600 years ago, but we won't see it happen for another 20 years. Just like the way that a firework explodes, and the sound takes some time to get to us.

[H4wkeye]

Yup.

You ever see a live fireworks display? You'll see the flash from one of them, then about a quarter second later, you hear the "boom". Sound takes time to get to you. So does light. We are around 620 light years from the star. That means that we see it as it existed 620 years ago. A telescope won't change that, but it will let us see it in more detail (if it's really big). What we see won't change, only the way we see it.

Because of the distance, it could have exploded 600 years ago, but we won't see it happen for another 20 years. Just like the way that a firework explodes, and the sound takes some time to get to us.

Ah i see,its more clear to me now,thanks.So basically we are seeing those distant objects with a big "lag".Events already occurred many years ago but we are seeing it as the light reaches us.

[pumpkinpie]

My 2 cents about pronunciation....I don't think it makes that much of a difference, as long as everyone knows what celestial object you are talking about!

[Fiery Phoenix]

Ah i see,its more clear to me now,thanks.So basically we are seeing those distant objects with a big "lag".Events already occurred many years ago but we are seeing it as the light reaches us.

Precisely.

My 2 cents about pronunciation....I don't think it makes that much of a difference, as long as everyone knows what celestial object you are talking about!

It can still be confusing, though.

[Ara Pacis]

How fast does gravity propogate? Would we be theoretically able to detect the shift in mass from an exploding star, such as bee/beh/bay-tel-juice/geece/gayce/gice?

[NEOWatcher]

How fast does gravity propogate? Would we be theoretically able to detect the shift in mass from an exploding star, such as bee/beh/bay-tel-juice/geece/gayce/gice?

Speed of light.
But; I'm not sure what you mean by "shift" in mass, it's all still there and , just more spread out. At this distance, the mass would have to travel quite a distance before we can detect any gravity effect. (if at all?)

[tdvance]

And of course, the gravity effect would be so weak we'd have a better chance detecting light or neutrinos first. Our gravity wave detectors are made for huge things like binary black holes about to collide.

[Ara Pacis]

Speed of light.
But; I'm not sure what you mean by "shift" in mass, it's all still there and , just more spread out. At this distance, the mass would have to travel quite a distance before we can detect any gravity effect. (if at all?)

That's what I was wondering, if we could detect the shift in mass from the expanding cloud of mass, perhaps through parallax, or not. Do we know through theory or observations that gravity propogates at the speed of light?

[Ara Pacis]

And of course, the gravity effect would be so weak we'd have a better chance detecting light or neutrinos first. Our gravity wave detectors are made for huge things like binary black holes about to collide.

But could we use some sort of interferometry to detect/resolve gravity better?

Also, it's a bit confusing because the term "gravity wave" seems to have two meanings. One is a gravity-balancing density shift and the other would seem to refer to gravitons or something.

[tdvance]

In this case, I mean, by gravity wave, that which would be, under wave-particle duality, equivalent to the graviton, in other words, ripples propagating in spacetime.

LIGO, the biggest gravity wave detector, does use interferometry, but still, I doubt it would detect a supernova.