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Off-Topic Discussion => General Discussion => Topic started by: Nuclear1 on January 20, 2011, 06:40:36 pm

Title: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Nuclear1 on January 20, 2011, 06:40:36 pm
http://www.huffingtonpost.com/2011/01/20/two-suns-twin-stars_n_811864.html

Quote
Earth could be getting a second sun, at least temporarily.

Dr. Brad Carter, Senior Lecturer of Physics at the University of Southern Queensland, outlined the scenario to news.com.au. Betelgeuse, one of the night sky's brightest stars, is losing mass, indicating it is collapsing. It could run out of fuel and go super-nova at any time.

When that happens, for at least a few weeks, we'd see a second sun, Carter says. There may also be no night during that timeframe.

The Star Wars-esque scenario could happen by 2012, Carter says... or it could take longer. The explosion could also cause a neutron star or result in the formation of a black hole 1300 light years from Earth, reports news.com.au.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Flipside on January 20, 2011, 07:01:57 pm
Quote
The Star Wars-esque scenario could happen by 2012, Carter says... or it could take longer

-1 for using the 2012 date to try and promote the event. This has been predicted for ages, and there's no reason for it to be 2012 any more than this year or 2013.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: iamzack on January 20, 2011, 07:16:32 pm
why would there be no night? is it gonna be on the other side of earth from the sun or what?
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Flipside on January 20, 2011, 07:23:25 pm
Might not be in the Northern Hemisphere, especially if it happens in Autumn, since Orion is an extremely prominent constellation here at night.

That said, I'm not certain if that is an exaggeration, but I suspect as much, it depends, obviously, on how bright the supernova is, which really can't be predicted.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: NGTM-1R on January 20, 2011, 07:29:09 pm
Chinese court astronomy records at least one supernova which basically wiped out nighttime for three days. It's not only possible, it's happened before.

It would depend on the season, but Orion is visible pretty much all night during the winter in the northern hemisphere.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Flipside on January 20, 2011, 07:31:48 pm
There was also the 1604 daylight supernova that created the crab nebula, as I said, possible, but 'turning night into day' is possibly a very poetic way of putting it, certainly, the ambient light factors would be up, but would it truly resemble 'day', or just night with a very bright moon?

edit: That said, looking at the effects of large meteors, it's not entirely impossible that we are talking a full blue-sky day here...

http://www.youtube.com/watch?v=_bJ9_XnqLOI
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: General Battuta on January 20, 2011, 07:37:36 pm
It could happen tomorrow or in ten thousand years. No reason to get excited.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Flipside on January 20, 2011, 07:42:29 pm
Oh, I'm excited, hope it happens soon, but I won't hold my breath either.

I note on youTube people are already getting completely the wrong idea about black holes....
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: watsisname on January 20, 2011, 07:45:21 pm
Ah yes, I think we looked into this before and found a supernova of Betelgeuse should appear slightly less bright than a full moon.  So it's not quite a "turn night into day" kind of thing, though it would be pretty brilliant point of light in the sky.  If anyone's seen an Iridium Satellite Flare (http://en.wikipedia.org/wiki/Satellite_flare#Iridium_satellite_flare), this would be a few magnitudes brighter than the brightest of those.  In other words, quite blatantly obvious in the night sky, and visible even in the daytime sky.

I just hope, if it goes off in our lifetimes, that it doesn't go off between June and August, as that's when Betelgeuse appears closest to the sun.  Any other time of year and it'd be easily visible during at least some part of night. :)
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: iamzack on January 20, 2011, 07:48:10 pm
i hope it goes off tomorrow and turns into a black hole and sucks up the whole universe that would be cool
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: MR_T3D on January 20, 2011, 07:56:29 pm
i hope it goes off tomorrow and turns into a black hole and sucks up the whole universe that would be cool
whoa, whoa, whoa.
whoa.
there are better ways to bring us all together, a black hole is pretty close to the bottom of my list, and maybe a few others as well.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Flipside on January 20, 2011, 08:00:14 pm
Well, as I understand black holes, which admittedly, is probably a fair bit out of date, collapsing into a Black Hole won't increase the gravitational effect of Betelguise in any way, it'll still have the same gravitic strength it always had, it'll just be compacted into a much smaller focus.

For example, if every last molecule of the Sun was instantly collapsed down until it formed a black hole, it would kill life on Earth, but the Earth itself would just keep orbitting the tiny black hole as it's centre of gravity, because the strength of the gravity would be the same.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Qent on January 20, 2011, 08:02:48 pm
http://www.huffingtonpost.com/2011/01/20/two-suns-twin-stars_n_811864.html

Quote
Betelgeuse, one of the night sky's brightest stars, is losing mass, indicating it is collapsing. It could run out of fuel and go super-nova at any time.
So what they mean is we might see it run out of fuel and asplode at any time? Ugh, confusing.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Flipside on January 20, 2011, 08:04:08 pm
Anyway, I thought it was losing diameter, not mass?
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: iamzack on January 20, 2011, 08:19:39 pm
Well, as I understand black holes, which admittedly, is probably a fair bit out of date, collapsing into a Black Hole won't increase the gravitational effect of Betelguise in any way, it'll still have the same gravitic strength it always had, it'll just be compacted into a much smaller focus.

For example, if every last molecule of the Sun was instantly collapsed down until it formed a black hole, it would kill life on Earth, but the Earth itself would just keep orbitting the tiny black hole as it's centre of gravity, because the strength of the gravity would be the same.

i know all that it was a joke if you take me srs one more time i swear i will draw a mustache on you while you sleep
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: SpardaSon21 on January 20, 2011, 08:23:40 pm
That statement is not intimidating because you don't know where we live.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: karajorma on January 20, 2011, 08:30:18 pm
Well, as I understand black holes, which admittedly, is probably a fair bit out of date, collapsing into a Black Hole won't increase the gravitational effect of Betelguise in any way, it'll still have the same gravitic strength it always had, it'll just be compacted into a much smaller focus.

It would actually have less of an effect. Stars lose mass when they go supernova. :)
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: watsisname on January 20, 2011, 08:47:50 pm
Betelgeuse isn't so much losing mass (it is losing a bit through solar wind, but that's another matter entirely) as it is running out of viable options for fusible material in its core.  Whereas our sun is only massive enough to produce elements up to helium (and thus will die once it has too much helium in the core, ending up as a white dwarf + planetary nebula), Betelgeuse is massive enough to produce elements all the way up to iron.  But once the star has an iron core, it can fuse no further because iron doesn't give off as much energy as it takes to put into fusing it.  The result is a supernova explosion as the core of the star collapses under its own weight and the outer layers get blasted off into space by the rebounding shockwave.

The reason Betelgeuse is shrinking in diameter is because it is a red supergiant star, so it has shells of various elements around its core that are undergoing fusion, and those shells give an unstable energy output.  The star regularly contracts and expands as a result, which is why we shouldn't really be surprised that it's contracting currently.  That contraction might just be part of a cycle which will continue for quite some time, or it might be a sign that it really is about to supernova.  We simply can't tell yet because we don't have data on what the core structure is like.

What Betelgeuse's structure might look like:
(http://img526.imageshack.us/img526/7052/redsupergiant.gif)

Note that we don't know what the central core is made of in Betelgeuse's case.  It might be up to Oxygen, in which case there's millions of years left until it supernova's, or it might be up to iron in which case it'll explode pretty much right now. :P
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Mars on January 20, 2011, 09:00:04 pm
Right now AKA 1000 years ago.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Rodo on January 20, 2011, 09:00:42 pm
Anyway... I've been waiting to see a nova, hope it happens during my lifetime.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Scourge of Ages on January 20, 2011, 09:11:08 pm
Right now AKA 1000 years ago.
I was gonna say that :P
This is really cool thinking about this and knowing that it propbably won't burn the life off of Earth, like Capella at point-blank range...
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: iamzack on January 20, 2011, 10:20:01 pm
(http://mimg.ugo.com/201002/38160/mandala.jpg)
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Nohiki on January 20, 2011, 10:25:54 pm
i hope it goes off tomorrow and turns into a black hole and sucks up the whole universe that would be cool

Till all are one! FOR CYBERTRON!
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Mefustae on January 21, 2011, 12:25:55 am
Pure nerdage.

I see... I understand now...

(http://lh4.ggpht.com/_eJlXVkGtmyI/SYdyEoRGXqI/AAAAAAAAAt4/VCLlx06ObRs/vlcsnap-10806082.jpg)

Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: FreeSpaceFreak on January 21, 2011, 03:44:16 am
Huh, according to Wikipedia (http://en.wikipedia.org/wiki/Near-Earth_supernova#Risk_by_type), a type 1a supernova (commonly caused by teeny weeny white dwarfs) is much more dangerous than other types (commonly caused by massive red giants). Why is that? It seems rather illogical.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: headdie on January 21, 2011, 05:20:09 am
Huh, according to Wikipedia (http://en.wikipedia.org/wiki/Near-Earth_supernova#Risk_by_type), a type 1a supernova (commonly caused by teeny weeny white dwarfs) is much more dangerous than other types (commonly caused by massive red giants). Why is that? It seems rather illogical.

try this
Quote from:  http://wiki.answers.com/Q/Are_supernova_dangerous_to_the_earth
near Earth supernova [See Link] is a supernova that occurs close enough to the Earth (less than 100 light-years away) to have noticeable effects on its biosphere. Gamma rays from a supernova induce a chemical reaction in the upper atmosphere, converting molecular nitrogen into nitrogen oxides, depleting the ozone layer enough to expose the surface to harmful solar and cosmic radiation. This has been proposed as the cause of the Ordovician extinction - [See link], which resulted in the death of nearly 60% of the oceanic life on Earth.
Type Ia supernova [See Link] are thought to be potentially the most dangerous if they occur close enough to the Earth. Because these supernova occur from dim, common white dwarf stars, it is likely that a supernova that could affect the Earth will occur unpredictably and take place in a star system that is not well studied. The closest known candidate is IK Pegasi [See Link]
Recent estimates predict that a Type II supernova would have to be closer than 26 light-years to destroy half of the Earth's ozone layer.

So basically a type 1a kicks out a greater density of gamma rays if i understand this right
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Flipside on January 21, 2011, 06:20:44 am
Well, as I understand black holes, which admittedly, is probably a fair bit out of date, collapsing into a Black Hole won't increase the gravitational effect of Betelguise in any way, it'll still have the same gravitic strength it always had, it'll just be compacted into a much smaller focus.

For example, if every last molecule of the Sun was instantly collapsed down until it formed a black hole, it would kill life on Earth, but the Earth itself would just keep orbitting the tiny black hole as it's centre of gravity, because the strength of the gravity would be the same.

i know all that it was a joke if you take me srs one more time i swear i will draw a mustache on you while you sleep

And if you get any more paranoid, I'll tell you that someone drew a mustache on you while you were asleep :p
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: newman on January 21, 2011, 07:13:37 am
Wikipedia states Betelgeuse is believed to be some 640 light years away. So if we see the nova tomorrow, it will have actually happened over 600 years ago, meaning it's entirely possible the Betelgeuse star doesn't exist anymore and hasn't for hundreds of years. I always wonder how many of the stars I see in the night sky don't exist anymore.. always found the thought intriguing.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Kosh on January 21, 2011, 09:09:27 am
Let's listen to the Bad Astronomer: (http://blogs.discovermagazine.com/badastronomy/2011/01/21/betelgeuse-and-2012/)

Quote
It’s the question of when that the two articles go off the rails. Betelgeuse may explode tomorrow night, or it may not go kerblooie until the year 100,000 A.D. We don’t know. But given that huge range, the odds of it blowing up next year are pretty slim. And clearly, the original article was really trying to tie in the 2012 date to this, even when it has nothing to do with anything. The tie-in was a rickety link to scuttlebutt on the web about it, but that’s about it.

What’s worse, the HuffPo article attributes the date to Dr. Carter himself, but in the original article he never says anything about it; the connection is all made by the article author. Given how popular HuffPo is, I imagine a lot of people will now think an actual scientist is saying Betelgeuse will blow up in 2012.

OK then, tell you what: I’m an actual scientist, and I would give the odds of Betelgeuse going supernova in 2012 at all — let alone close to December, the supposed doomsdate — as many thousands to one against. It’s not impossible, it’s just really really really really really really really unlikely.

Really.

So, doesn't sound like much.


Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Titan on January 21, 2011, 09:23:14 am
So how does this affect the first missions of FreeSpace?
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Pred the Penguin on January 21, 2011, 09:24:26 am
Still sounds like fun though... Not sure how'd it influence the Earth aside from night/day cycles of a few organisms if at all.

BUT BIG BOOM IS FUN!
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Shade on January 21, 2011, 09:28:47 am
Let's listen to the Bad Astronomer: (http://blogs.discovermagazine.com/badastronomy/2011/01/21/betelgeuse-and-2012/) Stuff.

Screw that. We were promised a big boom. Now they'd better deliver.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Nuclear1 on January 21, 2011, 03:05:03 pm
So how does this affect the first missions of FreeSpace?

NEBULA MISSIONS!!!!111
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Solatar on January 21, 2011, 03:44:42 pm
So how does this affect the first missions of FreeSpace?

Eve of Destruction involves the Orff being smashed by a supernova?
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: headdie on January 21, 2011, 04:46:09 pm
So how does this affect the first missions of FreeSpace?

Eve of Destruction involves the Orff being smashed by a supernova?

It would explain the engine failure
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: watsisname on January 21, 2011, 05:13:39 pm
Huh, according to Wikipedia (http://en.wikipedia.org/wiki/Near-Earth_supernova#Risk_by_type), a type 1a supernova (commonly caused by teeny weeny white dwarfs) is much more dangerous than other types (commonly caused by massive red giants). Why is that? It seems rather illogical.

try this
Quote from:  http://wiki.answers.com/Q/Are_supernova_dangerous_to_the_earth
near Earth supernova [See Link] is a supernova that occurs close enough to the Earth (less than 100 light-years away) to have noticeable effects on its biosphere. Gamma rays from a supernova induce a chemical reaction in the upper atmosphere, converting molecular nitrogen into nitrogen oxides, depleting the ozone layer enough to expose the surface to harmful solar and cosmic radiation. This has been proposed as the cause of the Ordovician extinction - [See link], which resulted in the death of nearly 60% of the oceanic life on Earth.
Type Ia supernova [See Link] are thought to be potentially the most dangerous if they occur close enough to the Earth. Because these supernova occur from dim, common white dwarf stars, it is likely that a supernova that could affect the Earth will occur unpredictably and take place in a star system that is not well studied. The closest known candidate is IK Pegasi [See Link]
Recent estimates predict that a Type II supernova would have to be closer than 26 light-years to destroy half of the Earth's ozone layer.

So basically a type 1a kicks out a greater density of gamma rays if i understand this right

No, they're just more dangerous because the progenitor stars for type 1a supernova (white dwarfs) aren't as noticeable as their type II counterparts (supergiants).  So it's possible that there's a white dwarf nearby that's about to go supernova which we haven't discovered yet.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Mongoose on January 21, 2011, 09:24:58 pm
Let's listen to the Bad Astronomer: (http://blogs.discovermagazine.com/badastronomy/2011/01/21/betelgeuse-and-2012/) Stuff.

Screw that. We were promised a big boom. Now they'd better deliver.
"There was supposed to be an Earth-shattering KABOOM!"
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Kolgena on January 21, 2011, 10:50:49 pm
Huh, according to Wikipedia (http://en.wikipedia.org/wiki/Near-Earth_supernova#Risk_by_type), a type 1a supernova (commonly caused by teeny weeny white dwarfs) is much more dangerous than other types (commonly caused by massive red giants). Why is that? It seems rather illogical.


try this
Quote from:  http://wiki.answers.com/Q/Are_supernova_dangerous_to_the_earth
near Earth supernova [See Link] is a supernova that occurs close enough to the Earth (less than 100 light-years away) to have noticeable effects on its biosphere. Gamma rays from a supernova induce a chemical reaction in the upper atmosphere, converting molecular nitrogen into nitrogen oxides, depleting the ozone layer enough to expose the surface to harmful solar and cosmic radiation. This has been proposed as the cause of the Ordovician extinction - [See link], which resulted in the death of nearly 60% of the oceanic life on Earth.
Type Ia supernova [See Link] are thought to be potentially the most dangerous if they occur close enough to the Earth. Because these supernova occur from dim, common white dwarf stars, it is likely that a supernova that could affect the Earth will occur unpredictably and take place in a star system that is not well studied. The closest known candidate is IK Pegasi [See Link]
Recent estimates predict that a Type II supernova would have to be closer than 26 light-years to destroy half of the Earth's ozone layer.

So basically a type 1a kicks out a greater density of gamma rays if i understand this right

No, they're just more dangerous because the progenitor stars for type 1a supernova (white dwarfs) aren't as noticeable as their type II counterparts (supergiants).  So it's possible that there's a white dwarf nearby that's about to go supernova which we haven't discovered yet.


I fail to see what good forewarning would do for us. "Hey guys, we're about to be cooked by gamma rays." "Really? Well ****."
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Mars on January 21, 2011, 10:55:09 pm
I think it's because there aren't any stars of sufficient size to go type II nova near us and cause a problem.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: FUBAR-BDHR on January 21, 2011, 11:04:17 pm
Aren't there 2 not only close enough by to wipe out the entire solar system but aimed right at us?  It's just a matter of when they did go off or will go off.  Gamma ray burst could arrive now or not for billions of years.   
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: karajorma on January 21, 2011, 11:44:32 pm
No, they're just more dangerous because the progenitor stars for type 1a supernova (white dwarfs) aren't as noticeable as their type II counterparts (supergiants).  So it's possible that there's a white dwarf nearby that's about to go supernova which we haven't discovered yet.

I don't think that's the problem. Notice the difference in distances mentioned? If a Type II supernova would have to be closer than eight parsecs (26 light-years) to destroy half the Earth's ozone layer but a Type Ia supernova would have to be closer than a thousand parsecs (3300 light-years) to affect the Earth, it suggests that the Type Ia is worse.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: carn1x on January 22, 2011, 12:38:54 am
Aren't there 2 not only close enough by to wipe out the entire solar system but aimed right at us?  It's just a matter of when they did go off or will go off.  Gamma ray burst could arrive now or not for billions of years.   

Well we better lose our minds just in case. Let the inevitable orgy begin!
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: watsisname on January 22, 2011, 03:27:45 am
No, they're just more dangerous because the progenitor stars for type 1a supernova (white dwarfs) aren't as noticeable as their type II counterparts (supergiants).  So it's possible that there's a white dwarf nearby that's about to go supernova which we haven't discovered yet.

I don't think that's the problem. Notice the difference in distances mentioned? If a Type II supernova would have to be closer than eight parsecs (26 light-years) to destroy half the Earth's ozone layer but a Type Ia supernova would have to be closer than a thousand parsecs (3300 light-years) to affect the Earth, it suggests that the Type Ia is worse.

waaaaaat.  I was thinking it was just because white dwarfs are more common and less visible, so that makes them a more likely and less visible threat.  If they really are more lethal at a given distance then that's interesting, and unexpected.  The source provided by wikipedia (http://www.tass-survey.org/richmond/answers/snrisks.txt) goes into some detail as to how those distance figures are determined.

On a quick skim through his conclusions seem correct, just rather counter-intuitive.  Type II supernovae are certainly far more energetic than type Ia, but most of that energy is in the form of neutrinos (which aren't too harmful since they basically pass right through anything without much interaction), whereas type Ia radiates more x-rays and gamma rays.  So even though they give off less energy, it's more energy of a form that is harmful to atmospheres and organisms.

Even so, I find the 1kpc figure for Ia supernova's destructive range extremely surprising.  That is a huge volume of space. :shaking:
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: headdie on January 22, 2011, 03:36:34 am
No, they're just more dangerous because the progenitor stars for type 1a supernova (white dwarfs) aren't as noticeable as their type II counterparts (supergiants).  So it's possible that there's a white dwarf nearby that's about to go supernova which we haven't discovered yet.

I don't think that's the problem. Notice the difference in distances mentioned? If a Type II supernova would have to be closer than eight parsecs (26 light-years) to destroy half the Earth's ozone layer but a Type Ia supernova would have to be closer than a thousand parsecs (3300 light-years) to affect the Earth, it suggests that the Type Ia is worse.

waaaaaat.  I was thinking it was just because white dwarfs are more common and less visible, so that makes them a more likely and less visible threat.  If they really are more lethal at a given distance then that's interesting, and unexpected.  The source provided by wikipedia (http://www.tass-survey.org/richmond/answers/snrisks.txt) goes into some detail as to how those distance figures are determined.

On a quick skim through his conclusions seem correct, just rather counter-intuitive.  Type II supernovae are certainly far more energetic than type Ia, but most of that energy is in the form of neutrinos (which aren't too harmful since they basically pass right through anything without much interaction), whereas type Ia radiates more x-rays and gamma rays.  So even though they give off less energy, it's more energy of a form that is harmful to atmospheres and organisms.

Even so, I find the 1kpc figure for Ia supernova's destructive range extremely surprising.  That is a huge volume of space. :shaking:

I suppose part of the problem is that in space there is very little to absorb and disperse the radiation so it is dangerous to a wider radius
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: karajorma on January 22, 2011, 04:10:00 am
I remember looking at that source a long time ago for some reason I can't remember and I was surprised that the Ia was more violent back then too.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Flipside on January 22, 2011, 08:10:47 am
It does seem odd, you would have thought that after that kind of distance, any effect would be so dispersed as to be almost negligable....
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: rscaper1070 on January 22, 2011, 09:56:10 am
IIRC it's because the gamma bursts are focused at the poles not the entire radius of the star. Like two gamma ray shotgun blasts.
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: FreeSpaceFreak on January 22, 2011, 11:05:46 am
On a quick skim through his conclusions seem correct, just rather counter-intuitive.  Type II supernovae are certainly far more energetic than type Ia, but most of that energy is in the form of neutrinos (which aren't too harmful since they basically pass right through anything without much interaction), whereas type Ia radiates more x-rays and gamma rays.

Oh, that explains it...
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: Astronomiya on January 22, 2011, 06:47:53 pm
Reading watsisname's source, the X-rays from a type Ia supernova aren't dangerous until it gets relatively close to us; it's the gamma rays that are more of a cause for concern.  Even so, I don't feel it's a huge cause.  50-100 pc might give us more reason to worry.

In any case, regarding Betelgeuse, it will explode sometime within the next 100,000 to million years.  That's all we can say, because once a star begins fusing helium, and those changes have made their way to the surface, any further changes in the core will generally not be seen by outside observers because it takes too long for radiative transfer to bring us this information (i.e., the changes make themselves felt outside the core, but because they are dependent on photons to relay this news, and photons take a really long time to make it out of a star, we may not see it before the star explodes).  For a 20 solar mass star like Betelgeuse, once carbon and oxygen burning commence in the core, it takes roughly 3-500 years for that supply to be exhausted and for the star to then begin fusing the products of that reaction (silicon, mostly) into heavier elements via alpha capture.  That process lasts about 6 months, until a core of iron builds up to the Chandrasekhar mass.  Once that happens, the core collapses in less than a second to become a neutron star, and the star explodes.

By contrast, the helium burning stage takes about a million years, and hydrogen burning about 10 million, again for a star with a mass like Betelgeuse's. 
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: ssmit132 on January 22, 2011, 07:58:11 pm
IIRC it's because the gamma bursts are focused at the poles not the entire radius of the star. Like two gamma ray shotgun blasts.
So would that mean that if one of the star's poles wasn't facing you, you would not get hit by the gamma rays?
Title: Re: Two Suns? Twin Stars Could Be Visible From Earth By 2012
Post by: FUBAR-BDHR on January 22, 2011, 09:40:56 pm
Pretty much.  Or not enough to matter.  It's those 2 that have an axis pointing right at us that are the ones to watch.