Brightest supernova ever observed

[Martin]

http://science.nasa.gov/headlines/y2007/07may_bigsupernova.htm?list45222

 

"Of all exploding stars ever observed, this was the king", said Alex Filippenko, who leads two of the observation teams involved in the discovery.

 

The star that exploded was 150 times as massive as the sun.

The explosion occurred in another galaxy, 240 million lightyears away, not in our Milky Way galaxy.

 

A new explosion-mechanism has been proposed, that applies only to these very massive stars.

By this mechanism, unlike other supernova models, the star can explode BEFORE it has exhausted its fusion fuel.

[Sayonara]

Staggering, to try and get your head around such a cataclysmic event.

 

These stars really are quite the drama queens, aren't they?

[Martin]

Sayonara, thanks for response. Yes it is staggering

 

100 types the energy of a typical supernova

http://space.newscientist.com/article/dn11799-did-antimatter-factory-spark-brightest-supernova.html

 

Also there is a star in our own galaxy, namely Eta Carinae, 7500 lightyears away, which is similarly near the upper mass limit and which has begun blowing away its outer layers by its own light pressure----and these astronomers say there is a chance that Eta Carinae could be headed for the same kind of explosion.

(no indication how soon though and not likely to bother us since 7500 LY is good and far but should be spectacular if and when)

[MolotovCocktail]

Also there is a star in our own galaxy, namely Eta Carinae, 7500 lightyears away, which is similarly near the upper mass limit and which has begun blowing away its outer layers by its own light pressure----and these astronomers say there is a chance that Eta Carinae could be headed for the same kind of explosion.

 

Do they have any idea when this will happen, and is as massive as the other star 240 million light-years away?

[Martin]

Do they have any idea when this will happen, and is as massive as the other star 240 million light-years away?

 

I've seen estimates for Eta Carinae of around 100 solar masses

which means in the same ballpark, maybe not quite as big as the other one.

 

I think in human terms---by our human-life timescale---I'd have to say no, there is no estimate of when it will happen, like in your lifetime, or in the next century.

 

But in astronomical terms, a million years is a short time, so suppose someone says "sometime in the next million years"

in one sense that is really pinning it down!

in another sense it gives no idea

 

We don't know whether or not to expect it in our own lifetime, so I would say they don't "have any idea".

 

this is my impression from what I remember of what I read. Maybe someone else will do some research and find a better estimate, that is not so vague.

[MolotovCocktail]

But in astronomical terms, a million years is a short time, so suppose someone says "sometime in the next million years"

in one sense that is really pinning it down!

in another sense it gives no idea

 

Yeah, good point. Its amazing that, on the one hand, 1 million years is so long for humans but on the cosmic timescale thats basically a blink of an eye!

 

I just read the article, and the one thing I found interesting was the involvement of antimatter and its creation. It seems to me that it was literally created right from the massive amount of energy from the blast. But such a phenomena can physically happen because energy and matter are interchangeable via E=mc^2, right?

[Martin]

Yeah, good point. Its amazing that, on the one hand, 1 million years is so long for humans but on the cosmic timescale thats basically a blink of an eye!

 

I just read the article, and the one thing I found interesting was the involvement of antimatter and its creation. It seems to me that it was literally created right from the massive amount of energy from the blast. But such a phenomena can physically happen because energy and matter are interchangeable via E=mc^2, right?

 

the energy equivalent of an electron (or equally well an antielectron) is 500 keV

 

ordinarily a photon of sun light has only around 1 eV more or less. so hundreds of thousands would have to merge together, if you wanted to make an electron/positron pair

 

it would never happen, it's like herding cats.

 

Now in the core of the sun where it is much hotter than at surface the thermal glow photons are, like 1500 eV.

there are 1 keV photons in the core of the sun----that is like dental Xray light.

 

That is not yet enough, but suppose you had a star that was 500 times hotter core than the sun core.

 

Then it would have 500 keV photons inside!

 

If two of those collide head-on and merge, then you have 1000 keV which is enough for a electron/positron pair!

-------------------------------------------

 

so this SOAKS UP ENERGY BY CREATING MATTER PARTICLES-----and that represents a new way for a star to die.

Because a star has to have enormous thermal energy in its core to keep its pressure up so it doesnt collapse.

that is why when they finally run out of fusion fuel they often do collapse

all you need is for the core to cool down a little bit and the outer layers smash down

 

so a star can die EVEN IF IT HASNT RUN OUT OF FUEL YET if it simply gets TOO HOT so that a lot of its thermal glow gammaray photons in the core have like 500 keV energy.

because then those gammaray photons become vulnerable to that kind of collision where they are annihilated and something else created (it doesnt have to be electron/positron pair it can be some other kind of matter)

=======================

 

There are still questions in my mind about this. I am just interpreting what I read and paraphrasing. Other people may want to add explanatory detail. I think there is a fine point: when a particle antiparticle pair is created the partners can get LOST in the crowd because the core is very big with a lot of random thermal activity.

so they wouldn't immediately rejoin each other and annihilate and make gammaray photons again. We should find out more detail about the reactions and the probabilities in this different kind of collapse.