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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."
http://news.discovery.com/space/why-does-a-star-explode.htm
This is the first result for the Google search "Why do stars explode".
Why is it so hot? Where am I going? What am I doing in this handbasket?
From what I remember from 6th grade science class:
Stars mainly use hydrogen/helium as nuclear fuel. However, once those run out, it begins to collapse as gravity takes over. The compression forces it to begin fusing heavier elements, which gives it a renewed burst of energy, thus causing it to explode outwards. You could argue that the heavier elements are still nuclear fuel, but it's not the primary fuel of the star throughout its life so that's basically just an argument of semantics.
Alternative explanation: Hollywood has taught us that random objects may explode at any moment, even in the absence of combustibles or pressure.
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).
The "burning" of the fuel is what generates the outward pressure that prevents a star collapsing under gravity, apparently. When it runs out of fuel to burn that outward pressure no longer exists, so gravitational collapse resumes, this time generating enormous energies and pressures. It "rebounds" and throws off its outer layers at stupendously high energy.
That is at least my layman's understanding of approximately how it works.
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.
It must have been something you assimilated. . . .
Only if you are entirely uninformed about American media. The CSM has no further connection to Christian Science in its editorial policy than the name its bylaws have stuck it with. (Even Mary Baker Eddy's desire that there be coverage of a religious theme has been opened up to any of the world's religions at all). It has won a number of Pulitzers and is one of the most respected publications in the country.
Alternative explanation: Hollywood has taught us that random objects may explode at any moment, even in the absence of combustibles or pressure.
Certain aspects of quantum theory teach us the same thing.
Almost, quantum theory explicitly requires an observer. Hollywood implicitly assumes observers paying $15 a ticket and another $40 for the BlurRay in 3 months. In fact, Hollywood assumes all possible observers will be observing and paying the full rates, so anything short of those predictions are losses due to piracy.
A gravitational collapse's release of energy doesn't need any nuclear reactions. Stuff simply falls down, so it converts gravitational potential energy into kinetic energy. Eventually it hits some other stuff hard, releasing said energy as photons.
A successful API design takes a mixture of software design and pedagogy.
...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.
You do realize that burning gasoline in your car engine doesn't change the mass of anything, right? That the mass of gas burned + mass of intake air = mass of exhaust?
And must like a catalytic converter will "burn" exhaust further, by subjecting it to different conditions, a star will briefly burn its own exhaust in the immense energy density that briefly exists as the star falls in on itself and reaches peak pressure before rebounding. All elements heavier than iron come from these brief moments in the large supernovas.
Socialism: a lie told by totalitarians and believed by fools.
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.
Lost at C:>. Found at C.
Well, that depends on whether it's a "first generation" star that began as just hydrogen or a second,third,fourth,etc. "generation" star that uses the gas from a previous star's supernova gas cloud thus incorporating some of the elements created during said supernova.
The Sun is still mostly hydrogen and helium but there are trrace amounts of other elements: http://csep10.phys.utk.edu/astr162/lect/sun/composition.html
Since the Earth has elements that aren't hydrogen and helium, we know our Sun isn't a "first generation".
So they're wrong about well established fact again. Wonderful.
The theory here was never well established fact. It was a long standing theory, because we've only recently had the tools to test it.
Right. Gravitational lensing would do the trick.
I come here for the love
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.
The fusion of heavier elements actually liberates less energy, and above some point (iron?) fusion of nuclei is a net loss of energy, which is why heavy elements are so much rarer than the lighter elements. They are all 'parasitic' losses of energy that are only produced during supernova.
A "binding energy" chart shows that light elements should be fused to release energy and heavy elements should be split to release energy. https://en.wikipedia.org/wiki/File:Binding_energy_curve_-_common_isotopes.svg
Which is where that whole bit about us being made of star dust comes from. It is not that we are formed of the same stuff that constitutes stars but that literally the atoms that make up our bodies, and most of our world were at some point formed inside a star.
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.
When you give advertising or subscription money to CSM, that's money going to CS.
That's the point of paying for a good service. You want the money to go to who is providing the service.
Well, as normally stated, quantum theory DOES require an observer. It does not require that the observer be sentient. Any electromagnetic interaction will do. Also strong or weak force interactions. Probably gravity, too, but that's just a bit difficult to observe.
Typically experiments use electrons or photons as the primary observers, but nearly anything will work, with varying degrees of sensitivity.
OTOH, as a believer in the Many-Worlds interpretation, I think that the observation just details which of the worlds you have ended up in. And I also believe in multiple pasts as well as multiple futures. (And the only thing special about this present, is that it's the one that you are observing from.)
I think we've pushed this "anyone can grow up to be president" thing too far.
Just because something is sponsored by a religious group doesn't automatically make it bad. Many christian groups give large sums of money to charity. Others build awesome churches (mormons build awesome temples, though i don't agree with their views), and others sponsor scientific advancement. Be glad that these organisations are grabbing money from suckers, that money often goes to good causes. Unless it's a blatant cult like scientology, then they can go fuck themselves
If you gave me a choice between a printer and a giraffe with explosive diarrhoea, i'll get my ladder and my raincoat
You do realize that burning gasoline in your car engine doesn't change the mass of anything, right? That the mass of gas burned + mass of intake air = mass of exhaust?
... = mass of exhaust + mass equivalent of energy released
That's tiny in the case of gasoline in a car, but far from negligible for the sun:
The sun loses about four million tons per second this way.
(Although, in relative terms, it's negligible for the sun as well...)
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.