Runaway Anti-Matter Production Makes for a Spectacular Stellar Explosion

[Posteritatis]

Boom. Very, very boom.

ScienceDaily (Jan. 5, 2010) — University of Notre Dame astronomer Peter Garnavich and a team of collaborators have discovered a distant star that exploded when its center became so hot that matter and anti-matter particle pairs were created. The star, dubbed Y-155, began its life around 200 times the mass of our Sun but probably became "pair-unstable" and triggered a runaway thermonuclear reaction that made it visible nearly halfway across the universe.

Y-155 exploded about 7 billion years ago, when the universe was half its current age. It was discovered in the constellation Cetus (just south of Pisces) with the National Optical Astronomy Observatory's (NOAO) 4-m Blanco telescope in Chile in November of 2007 during the last weeks of the six-year ESSENCE project. The Keck 10-m telescope in Hawaii, the 6.5-m Magellan telescope in Chile, and the MMT telescope in Arizona rapidly focused on the new star, revealing that the wavelengths of light emitted from the supernova were stretched or "redshifted" by 80% due to the expansion of the universe.

Once the distance to the explosion was established, Garnavich and his collaborators calculated that, at its peak, Y-155 was generating energy at a rate 100 billion times greater than the sun's output. To do this, Y-155 must have synthesized between 6 and 8 solar masses of radioactive nickel. It is the decay of radioactive elements that drives the light curves of supernovae. A normal "Type Ia" thermonuclear supernova makes about one tenth as much radioactive nickel.

"In our images, Y-155 appeared a million times fainter than the unaided human eye can detect, but that is because of its enormous distance," Garnavich said. "If Y-155 had exploded in the Milky Way it would have knocked our socks off."

Even without the fact that the phrase "runaway antimatter production" shows up in the headline there, I struggle to comprehend those kinds of energies.

[valerief]

1. A whale of a boom! nt

[Ready4Change]

2. Any physics knowledgeable people able to explain this?

How is this producing matter/antimatter pairs? Never heard of that process.

[Posteritatis]

3. Sheer pressure and temperature, from what I can tell.

That was a big star, and it was trying to collapse in on itself there.

[Fumesucker]

4. I found this explanation..

I hadn't heard of these types of supernovae either so I did a little research..

http://eemorningwood.tumblr.com/post/273154154/antimatter-supernova-the-largest-explosion-ever

At sizes of around four megayottagrams (that’s thirty-two zeros) giant stars are supported against gravitational collapse by gamma ray pressure. The hotter the core, the higher the energy of these gamma rays - but if they get too energetic, these gamma rays can begin pair production: creating an electron-positron matter-antimatter pair out of pure energy as they pass an atom. Yes, this does mean that the entire stellar core acts as a gigantic particle accelerator.

The antimatter annihilates with its opposite, as antimatter is wont to do, but the problem is that the speed of antimatter explosion - which is pretty damn fast - is still a critical delay in the gamma-pressure holding up the star. The outer layers sag in, compressing the core more, raising the temperature, making more energetic gamma rays even more likely to make antimatter and suddenly the whole star is a runaway nuclear reactor beyond the scale of the imagination. The entire thermonuclear core detonates at once, an atomic warhead that’s not just bigger than the Sun - it’s bigger than the Sun plus the mass of another ten close by stars.

The entire star explodes. No neutron star, no black hole, nothing left behind but an expanding cloud of newly radioactive material and empty space where once was the most massive item you can actually have without ripping space. The explosion alone triggers alchemy on a suprasolar scale, converting stars’ worth of matter into new radioactive elements.

[HCE SuiGeneris]

5. Too cool.

Thanks, FS!

[Ready4Change]

8. Woof! Thanks.

Very interesting that something could be too BIG to collapse on itself, and that they may have found one. Thanks for digging up the description!

[Posteritatis]

10. If a star gets big enough...

The force of the light from the thing is enough to stabilize or even destroy it. It basically glows itself apart.

There's another "I cannot possibily comprehend the scale of these energies" moment for you.

[caraher]

9. Wikipedia has a decent article on this

They're called pair-instability supernovas

[tinrobot]

6. Screw fusion reactors

Let's generate some gamma rays and make an antimatter reactor.

:sarcasm:

[Vinnie From Indy]

7. A great book if you are into this kind of thing is

"Death from the Skies" by Phil Plait. Plait is an astronomer that details a laundry list of ways that the universe could sterilize the Earth in the blink of an eye.

While the above supernova is truly an awesome thing, it ain't got nothing on a Gamma Ray Burst caused by the birth of a massive black hole. In fact, if aimed exactly right, a Gamma Ray Burst from thousands of light years away could kill every living thing on Earth (excepting maybe bacteria living deep within the Earth and feeding on radioactive elements.)

The book is very entertaining and eye opening!

Cheers!

[Fumesucker]

11. I read "Calculating God" by Robert J Sawyer recently..

It's an SF book but apparently Sawyer is quite knowledgeable in the sciences..

He makes the point in the book that supernovae are necessary not only for life but also for the development of planets in the first place. It is supernovae that trigger the collapse of gas/dust clouds into solar systems, too few supernovae and there will be no or very few planetary systems, too many supernovae and all life on the many planets formed will be sterilized. Like many phenomena leading to the existence of life in our universe it's a very delicately balanced process.

[Vinnie From Indy]

12. Every cell in your body was born in a supernova

After the big bang, there were basically two elements in the universe - hydrogen and helium. Every other element came after this event. These gasses condensed into stars that eventually exploded in a supernova. It was billions and billions of supernova over the span of billions of years that manufactured all the elements we know today. No supernova - no life.

I will check out that book! :)

Cheers!