Scientists Forced To Reexamine Theories In Light of Massive Gamma-Ray Burst

cold fjord writes "Earlier this year we discussed news of a shockingly powerful gamma-ray burst. Scientists have had time to study the phenomenon, but it's not offering up any easy answers. The Christian Science Monitor reports, 'An exploded star some 3.8 billion light-years away is forcing scientists to overhaul much of what they thought they knew about gamma-ray bursts – intense blasts of radiation triggered, in this case, by a star tens of times more massive than the sun that exhausted its nuclear fuel, exploded, then collapsed to form a black hole. Last April, gamma rays from the blast struck detectors in gamma-ray observatories orbiting Earth, triggering a frenzy of space- and ground-based observations. Many of them fly in the face of explanations researchers have developed during the past 30 years ... "Some of our theories are just going down the drain," said Charles Dermer, an astrophysicist at the Los Alamos National Laboratory in New Mexico ... while typical long-duration bursts last from a few seconds to a few minutes, GRB 130427A put on its display for 20 hours. ... [W]ith GRB 130427A, some of the highest energy photons, including the new record-holder, appeared hours after the blast. "This is hard to explain with our current models," Dermer said. In addition, gamma rays and emissions at visible wavelengths brightened and dimmed in tandem, quite unexpected because theory suggested they come from different regions of the expanding shells of material and thus should have peaked and dimmed at different times. Finally, theorists had posited different mechanisms for generating gamma rays and X-rays that are part of the light show a long-duration gamma-ray burst puts on. The result should have been a fadeout for the two forms of light punctuated by periods where emissions were interrupted. Instead, the two dimmed smoothly. The theoretical edifice GRB 130427A is eroding has been 46 years in the making.' — The 21 November 2013 Science Express has abstracts for four related papers (first, second, third, fourth). More at Sky & Telescope and NASA."

Re:Question

[bflong]

http://news.discovery.com/space/why-does-a-star-explode.htm [discovery.com]

This is the first result for the Google search "Why do stars explode".

Re:Question

[ChronoReverse]

Regular star fuel is hydrogen (and helium very late) which undergoes fusion.

When this fuel is exhausted, the star collapses under its own gravity. This can be extremely sudden (even in human terms).

The collapse can only go so far before the star is compressed to its limit. Where this limit is depends on how massive the star is. Unless the star is massive enough to crush right into a black hole, the collapse will also stop suddenly and "bounce back" as the core instantly reheats from the compression. This is the supernova explosion as all the stuff that normally wouldn't fuse goes and fuses anyway (this is where elements past iron come from).

Re:Question

[alexander_686]

You might then want to read up on it. The Christian Science Monitor has been around for a long time and has a strong record of integrity and high quality reporting. While owned by the CS the news side is segregated from the editorial side like most reputable newspapers. And the news side dominates. One of the better national newspapers of the US.

Re:Question

[Anonymous Coward]

The Christian Science Monitor is owned by the 'Church of Christ, Scientist'; however the church doesn't interfere with the magazine.

Despite it's name and provenience, it's actually a well respected and credible organization.

No creationism or other superstitious nonsense there.

Comment removed

[account_deleted]

Comment removed based on user account deletion

Re:Dispersion, anyone?

[tibit]

Let's face it: over 3 billion light years, it doesn't take much dispersion for things to arrive with a 20 hour delay. We're talking parts-per-trillion here.

Re:Question

[MiniMike]

...what mass does a star have besides the helium and hydrogen that should be all gone at this point?

The hydrogen and helium are not gone, they're just converted (via fusion) to higher number elements which require more extreme conditions to be used as fuel. The fusion reaction is what releases the energy in a star, not a pure conversion of hydrogen to energy.

Re:Question

[gstoddart]

It's own gravity is due to its own mass. However, if all fuel is exhausted, then what mass remains that the star is still endowed with such immense gravity? That is, what mass does a star have besides the helium and hydrogen that should be all gone at this point?

First of all, I'm not a physicist.

But, the fusion happening in a star means it's taking the hydrogen and helium and turning it into heavier elements like iron and the like. It's not "burning" fuel in the sense of consuming it and leaving smoke, but crazy big nuclear reactions are energetically making heavier kinds of matter (that's what fusion means, things are getting stuck together, as opposed to fission which is ripping things apart).

Once the crazy big nuclear reaction runs out, the forces keeping the star occupying a larger volume stop, and everything collapses in on itself.

Once that happens, it makes a really really big boom. Because eleventy zillion tons of hot iron and other stuff collapsing onto itself is, to make a huge understatement, exceedingly energetic -- to the point that it can briefly kick out things like gamma rays. (Because, as far as I understand, the magnitude of the collapse is well beyond anything we could even ponder and has a mass likely millions or billions of times that of the Earth.)

So the star hasn't exhausted its mass, it has exhausted its fuel. And then a really vast amount of mass collapses in on itself under its own gravity. And then we see some of the most energetic events we can even fathom. And the crazy collapse under gravity pushes matter to even more ridiculous levels of density, and then releases even more energy.

At least, that's my best understanding of it. I'm sure several people will tell me how horribly wrong I am. I already know it's horribly simplified.

Re:not unusual

[similar_name]

There's hardly well established fact in science. There are observations. Theories are explanations of those observations. Given our observations, we make an explanation. That's called a theory. When an observation contradicts that explanation we adjust the explanation or wind up replacing it. That's how progress goes. I agree though, not unusual for science to respond to new observations.

Re:yeah, newspaper of a child-killing cult

[Anonymous Coward]

Handily, there's a name for your post. It's called the Genetic Fallacy.

While it is true that the person starting the publication was roundly dismissed for her "science" (and for that matter, roundly dismissed by mainstream Christianity for her "Christianity")... that is completely irrelevant to the quality of the publication today. In spite of, or perhaps even attributable to extra scientific caution in a "defensive" reaction to that history, it is now quite highly-regarded for the scientific soundness of its articles.

Henry Ford was virulently antisemitic. Do you attack acquaintances today who own Ford cars? No need to answer. If (when) we reviewed your daily life, we'd undoubtedly find there is one and only one issue to which you apply this "logic"--religion.

Re:Question

[the_other_chewey]

At least, that's my best understanding of it. I'm sure several people will tell me how horribly wrong I am. I already know it's horribly simplified.

I am a physicist, and no: As simplified explanations go, yours is a pretty good one.