Challenge theoretical models, Crab pulsar beams most energetic gamma rays ever detected from a pulsar

Oct 06, 2011
This is an artist's conception of the pulsar at the center of the Crab Nebula, with a Hubble Space Telescope photo of the nebula in the background. Researchers using the Veritas telescope array have discovered pulses of high-energy gamma rays coming from this object. Credit: David A. Aguilar (CfA) / NASA / ESA

A thousand years ago, a brilliant beacon of light blazed in the sky, shining brightly enough to be seen even in daytime for almost a month. Native American and Chinese observers recorded the eye-catching event. We now know that they witnessed an exploding star, which left behind a gaseous remnant known as the Crab Nebula.

An international collaboration of astrophysicists, including a group from the Department of Physics in Arts & Sciences at Washington University in St. Louis, has detected pulsed gamma rays from the neutron star at the heart of the Crab Nebula with energies far higher than the common theoretical models can explain.

The pulsed gamma rays had energies between 100 and 400 billion electronvolts (Gigaelectronvolts, or GeV), far higher than 25 GeV, the highest energy radiation from the neubla previously detected. A 400 GeV photon is 11 orders of magnitude – almost a trillion times – more energetic than a visible light photon.

The high-energy emission was detected by the VERITAS array of four 12-meter Cherenkov telescopes in Arizona that looks for the fleeting signatures of gamma-ray collisions with Earth's atmosphere in the skies overhead. The research is published in the Oct. 7 issue of Science.

This is an X-ray image of the Crab Nebula and pulsar. Credit: Image courtesy of the Chandra X-ray Observatory, NASA/CXC/SAO/F. Seward.

"We presented the results at a conference and the entire community was stunned," says Henric Krawczynski, PhD, professor of physics at Washington University. The WUSTL group led byJames H. Buckley, PhD, professor of physics, and Krawczynski is one of six founding members of the VERITAS consortium.

The Crab Nebula is the spectacular remains of a massive star that became a supernova in the year 1054 and was brilliant enough that its flaring was recorded by Chinese and Arab astronomers. The collapsed core of the defunct star, a pulsar discovered only in 1969, is only 30 kilometers in diameter but pumps out enormous amounts of energy, making the nebula 75,000 times brighter than the Sun. The dance of the high-energy particles spewed by the star and its strong magnetic field fill the inner nebula with phantasmagoric, ever-changing shapes like expanding rings made up flickering knots and turbulent high-speed jets.

Jets of particles stream out of the pulsar's magnetic poles, producing powerful beams of light. Because the magnetic field and the star's spin axis are not aligned, these beams sweep out a circle in space, crossing the line of sight from Earth at regular intervals, so that the emission appears to pulse.

"The pulsar in the center of the nebula had been seen in radio, optical, X-ray and soft gamma-ray wavelengths," says Matthias Beilicke, PhD, research assistant professor of physics at Washington University. "But we didn't think it was radiating pulsed emissions above 100 GeV. VERITAS can observe gamma-rays between100 GeV and 30 trillion electronvolts (Teraelectronvolts or TeV).

This image of the Crab Nebula combines visible light (green) and radio waves (red) emitted by the remnants of a cataclysmic supernova explosion in the year 1054. and the x-ray nebula (blue) created inside the optical nebula by a pulsar (the collapsed core of the massive star destroyed in the explosion). The pulsar, which is the size of a small city, was discovered only in 1969. The optical data are from the Hubble Space Telescope, and the radio emission from the National Radio Astronomy Observatory, and the X-ray data from the Chandra Observatory. Credit: X-ray: NASA/CXC/ASU/J. Hester et al.; Optical: NASA/HST/ASU/J. Hester et al.; Radio: NRAO/AUI/NSF

Scientists had looked at the higher energy range before but with instruments that had much lower sensitivities than VERITAS.

Beilicke, Buckley and Krawczynski are members of WUSTL's McDonnell Center for the Space Sciences in Arts & Sciences.

Nepomuk Otte, PhD, a VERITAS scientist and a postdoctoral researcher at the University of California, Santa Cruz, advocated using the powerful gamma-ray observatory to look at the pulsar, even though the emission cut-off was thought to be much lower than the telescopes trigger energy.

The VERITAS team turned the telescope to the pulsar for 107 hours over a period of four years. To everyone's surprise, they found a very high energy pulsed emission.

They can be absolutely certain the high-energy beam is coming from the pulsar because it has exactly the same period as the pulsed radio and X-ray emissions that have long been observed.

Models of pulsar emission worked out to explain these earlier observations can't explain the VERITAS result without major adjustments.

The VERITAS result doesn't fit with standard models of pulsar emission. The pulsar is surrounded by a plasma-filled superconducting magnetosphere that rotates rigidly with the star except where there are open field lines. (The "light cylinder" marks the boundary where plasma rotates at the speed of light to stay with the pulsar.) Particles accelerated across "vacuum gaps" in the magnetosphere emit the electromagnetic radiation such as gamma rays. Still unresolved is the location of the gaps and the mechanism by which the radiation is produced. Among the leading candidates are the polar cap, slot gap and outer gap models. Credit: Magic Collaboration

Whatever the details, some extreme physics is involved. "Electrons and protons whipping off the surface of the neutron star create a cylindrical superconducting magnetosphere that is about a thousand kilometers in diameter and rotates rigidly with the neutron star," Krawczynski says.

"The cylinder is superconducting but somewhere little gaps open, and particles are accelerated to very high energies across these gaps, like giant lightning strikes. The objective of the observations is to locate the gaps and to identify the mechanism by which particles are accelerated and gamma rays are emitted."

One theory is that particles are accelerated along the open field lines near the polar caps of the pulsar. A second, called the outer gap theory, is that they grow in the outer magnetosphere where regions of opposite charge meet. Each location favors different mechanisms for the production of radiation.

"It would be extremely difficult for the polar cap model to account for the data points VERITAS has found," Beilicke says. "But, as always, reality is complicated. It's possible the radio emission could still be coming from the polar cap and the hard X-ray and gamma-ray emission originate from a different particle population accelerated in the outer gap. We're not yet at a point where we can rule out any of the scenarios."

"The finding shows that the theory is not there yet," Krawczynski says. "We know less about these systems than we thought."

The new finding is one of the most exciting results at VERITAS since it saw first light in 2007, he adds. It ranks right up there with discovery of very-high-energy gamma ray emission from a location very close to a supermassive black hole in the giant radio galaxy Messier 87 and the discovery of gamma rays from the starburst galaxy M82, an extremely busy stellar nursery.

Explore further: Planet-forming lifeline discovered in a binary star system

More information: VERITAS (Very Energetic Radiation Imaging Telescope Array System) is a ground-based observatory for gamma-ray astronomy located at the Fred Lawrence Whipple Observatory in southern Arizona. It is an array of four 12-meter optical reflectors, used to record Cherenkov radiation created by high-energy gamma-ray showers in the atmosphere. These imaging Cherenkov telescopes have maximum sensitivity in the energy range from 100 GeV to 10 TeV (10,000 GeV or 10 trillion electron volts).

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Nanobanano
1.7 / 5 (6) Oct 06, 2011
Very interesting.

This is around 100 times the energy level that could be explained even by neutron-anti-neutron annihilation at ordinary velocities...

However, the relativistic mass of relativistic anti-neutrons colliding on the surface under the trillions of meters per second gravitational acceleration at the surface of the star might explain it, since the relativistic mass of the neutrons and anti-neutrons created in the proton-proton collisions would be near the speed of light,a nd therefore relativistic mass perhaps a few dozen to a few hundred times greater than the "rest mass".

So if a neutron and anti-neutron collided with a relative velocity of 0.9999c, it should produce gamma rays near 100GeV...

This at least partially confirms my theory that the Crab Nebula exploded in a matter-anti-matter annihilation event...and continues to have small matter-anti-matter annihilation events on it's surface at relativistic energy levels under gravitational collapse...
Neurons_At_Work
4.6 / 5 (9) Oct 06, 2011
I am genuinely shocked that He-Who-Shall-Not-Be-Named did not wind up with the Nobel Prize for Physics. Clearly the judges are both short-sighted and ignorant of the many contributions made by certain contributors to this illustrious forum.
omatranter
2.8 / 5 (13) Oct 06, 2011
"It turns out that being persistent and stubborn helps,"

I couldn't agree more, but would add that ignorance and a total disregard for facts help a great deal, need I say more, yes, Repulsive Neutrons Rule!
yyz
5 / 5 (6) Oct 06, 2011
It should be interesting to hear how this tremendous pulsed energy jet from the pulsar is totally masked by a "semi-rigid" metal enriched shell a few thousand miles from the alleged pulsar at the center of our Sun. And how the shock wave produced by the interaction of the high energy radiation from the pulsar, seen at distance of 10 light days from the Crab pulsar, manages to extend only a few thousand miles from our Sun: http://arxiv.org/...2868.pdf

Or explaining away the explosive accelerating shock front that should exist several parsecs from the Sun's putative pulsar: http://arxiv.org/...84v1.pdf

Additionally, there's the lack of a gamma-ray bubble similar to that observed at our galaxy's nucleus (and copiously cited by OKM as evidence of neutron repulsion): http://arxiv.org/...34v1.pdf

The paper describing the VERITAS results can be found at: http://arxiv.org/...3797.pdf
omatumr
1.3 / 5 (16) Oct 06, 2011
The same object that dazzled skygazers in 1054 C.E. continues to dazzle astronomers today by pumping out radiation at higher energies than anyone expected.


The answer was still hidden in nuclear rest mass data - and unavailable to the observers in 1054 AD: Neutron repulsion.

www.omatumr.com/D...Data.htm

The answer was still not recognized 903 years later, in 1957.

It was published on the front cover of the 1999 ACS Proceedings on the "Origin of Elements in the Solar System: Implications of Post-1957 Observations"

http://ebookee.or...099.html

That is the energy source that powers:

a.) Compact embers of stars
b.) The Sun and other ordinary stars
c.) Accelerated expansion of the universe.

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo
yyz
4 / 5 (8) Oct 06, 2011
@Oliver,

Neither of those links even mentions the observations I referenced, much less explain the inconsistencies I noted. Semi-rigid metal enriched regions in the photosphere the sun A)do not exist and B) do not totally absorb VHE jets of energetic particles emanating from your alleged pulsar.
omatumr
1.5 / 5 (16) Oct 06, 2011
@Oliver,

Semi-rigid metal enriched regions in the photosphere the sun

A) Do not exist and

B) Do not totally absorb VHE jets of energetic particles emanating from your alleged pulsar.


A. The Semi-rigid metal enriched regions are below the fluid photosphere of waste products from the pulsar.

B. The distinguished Professor of math, physics and chemistry at ANU, Dr. Barry Ninham (ANU), provided the missing key to solar eruptions in 1963 [1].

Professor Ninham helped Professor Stig Friberg and I use that key to explain solar eruptions and climate change in 2002 [2]:

Expulsion of magnetic fields by the Meisner effect, driven by the rotating superconducting, super-fluid of iron-rich material that surrounds the pulsar core [1,2]

1. B. W. Ninham, Charged Bose gas in astrophysics, Physics Letters 4, 278-279 (1963).

2. Super-fluidity in the solar interior: Implications for solar eruptions and climate, J Fusion Energy 21, 193-198 (2002).

http://arxiv.org/.../0501441
omatumr
1.3 / 5 (14) Oct 06, 2011
This talented young astrophysicist, Dr. Nepomuk Otte, displayed great insight into the workings of honest science!

"It turns out that being persistent and stubborn helps," Otte said.

"These results put new constraints on the mechanism for how the gamma-ray emission is generated."

Congratulations, Dr. Otte!

Your comments in the original story have disappeared!

Despite Big Brother's censorship, may others learn your to appreciate your tenacity in relying on experimental observations instead of government models and government propaganda.
yyz
5 / 5 (4) Oct 06, 2011
"The Semi-rigid metal enriched regions are below the fluid photosphere of waste products from the pulsar."

If a solar-mass pulsar is present, then at what solar declinations are we to find the interaction between the bipolar GeV particle beams from the pulsar and your "semi-rigid metal enriched regions" (which helioseismology fails to detect)? These areas should be brightly emitting across a wide range of the EM spectrum (GR to radio) and should be easily detected and mapped even located far beneath the photosphere.

Interactions of this energetic bipolar jet with a "semi-rigid" layer should also generate acoustic vibrations easily detectable using helioseismology. Where is the helioseismic data to back up your claims?

I'm sure you understand the impact of these questions. An honest answer (even "I don't know") would be preferable to the usual irrelevant or insufficient replies.

With kind regards,

yyz
omatumr
1 / 5 (9) Oct 07, 2011
I'm sure you understand these questions.


I will respond to questions, as time permits, but I do not have time to argue with those who will not read information published in peer-reviewed papers [1-6].

1. Distinguished ANU Professor of math, physics and chemistry: B. W. Ninham, Charged Bose gas in astrophysics, Physics Letters 4, 278-279 (1963)

2. "Composition of the solar interior: Information from isotope ratios"
http://arxiv.org/...410717v1

3. "Super-fluidity in the solar interior: Implications for solar eruptions and climate"
http://arxiv.org/.../0501441

4. "Solar abundance of elements from neutron-capture cross sections"
http://www.lpi.us...1033.pdf

5. "The Sun is a plasma diffuser that sorts atoms by mass"
http://arxiv.org/.../0609509

6. "Origin of Elements in the Solar System:"
http://ebookee.or...099.html
jsdarkdestruction
5 / 5 (5) Oct 07, 2011
thats garbage oliver, you cant explain it because you are wrong. those links you wrote dont count as evidence and half the real stuff you link to doesnt support you in any way, in fact the majority of the time they dont even have anything to do with the question. get real oliver, its pathetic.
Standing Bear
1.7 / 5 (6) Oct 07, 2011
Hmmmm, rotating at the speed of light...and then there are....GAPS. Could it be that 'c' is exceeded in these special regions. After all, normal physics is probably broken in these unverifiable placees anyway. But go ahead, worship dogma and let us twist in the wind for another hundred years or two until something undeniable takes place, or some sense materializes politically to put the skeptics out of business for a while, in jail, or at least marginalized long enough to get us a working warp drive. Look at what kind of hatchet job these luddite true believer are doing on the neutrino researchers. Like life on other worlds. We will refuse believe in extraterrestrial life up to when we fail to sanitize some sample return from Mars, for instance, and the resulting pandemic kills a billion people. Then we will believe because we will be collectively and murderously forced to believe. Of course our leaders know already and the proof is...classsssified!
Mayday
not rated yet Oct 07, 2011
These beams of high energy gamma rays -- at what distance would they be dangerous to life on a planet similar to Earth? At what distance would they be dangerous to an astronaut in a craft similar to the ISS?
yyz
5 / 5 (5) Oct 07, 2011
"I will respond to questions, as time permits, but I do not have time to argue with those who will not read information published in peer-reviewed papers [1-6]."

Oliver, I read all six of the papers you "responded" with, and there was not a single mention in any of them concerning jets from the solar "pulsar" I inquired about or the interaction of the jets with the "semi-rigid metal enriched regions" (still undetected by helioseismology). In point of fact, none of the references you list on this thread contain any mention of pulsar jets in the sun. How about giving some published references that actually discuss what I asked about.

And did you read the papers I linked to referring to the extremely energetic near-field (parsec-scale) environment of pulsars? How a thin layer of plasma a few thousand kilometers in radius can completely shield the solar system from the pulsar's energetic jets defies explanation (as evident by your lack of references supporting your position).
antialias_physorg
not rated yet Oct 07, 2011
These beams of high energy gamma rays -- at what distance would they be dangerous to life on a planet similar to Earth?

What do you mean by 'dangerous'? A gamma photon retains its DNA damaging abilities no matter how far away you are from the source (with the exception of redshift from sources very far away - but that is pretty negligible). The closer we are to the source and the more intense the source the more of these gamma photons will hit the Earth.

A gama ray flash from a supernova in a few dozen lightyear radius could very well sterilize the earth (or the shockwave could cause atmospheric changes that would kill off most atmosphere-dependent life). Jets from intense sources (pulsars, black holes...) could be dangerous much further out than that.

Astronauts in their flimsy craft (like the ISS) are already endangered by radiation from the sun. That is why they are encouraged not to have kids after going into space.
Raygunner
not rated yet Oct 07, 2011
The light cylinder is interesting. Could it be that at the edge of the cylinder the rotating fields, gaps and all, interact with parts of the field that extend OUTSIDE the cylinder and have decoupled (or broken away) from the inside field edges rotating at c? The fields extend beyond the cylinder so the c boundary interface must have some extreme effects as segments of flux break away when c is reached, effectively "spinning down" as the distance beyond the cylinder wall increases. As the field breaks/snaps at the c boundary, the drag or interaction could create some pretty extreme relativistic effects depending on the flux energies involved. This could happen 100's or 1000's times a second. Also, the c interface might be a very sharp transition, maybe just a few meters wide. Just a layman here spouting my 2 cents.
Tuxford
1.6 / 5 (7) Oct 07, 2011
LaViolette has updated his blog regarding his longstanding contention that the pulsar is simply not the primary source of illumination for the nebula. Instead it originates from a passing galactic core superwave of cosmic rays. This model was proposed first in his 1983 dissertation.

http://starburstf...aveblog/

And recent supporting news:

http://www.physor...ula.html

http://www.physor...dog.html
Ethelred
3.7 / 5 (3) Oct 08, 2011
I will respond to questions, as time permits, but I do not have time to argue with those who will not read information published in peer-reviewed papers [1-6].
You have plenty of time to spam the hell out of Physorg and other sites. I read all your stuff. So have many others here and those in particular are the people you ignore. SO lets see you take the time to answer these questions by someone that HAS READ ALL YOUR STUFF. Including the non-peer reviewed stuff you link to.

Where is evidence for Iron in the those solar flare images you like to use? They only had TRACES of iron.

Where is the evidence that neutrons repel each other in a way that is different from the Pauli Exclusion Principle?

Where is someone, someone remotely competent as opposed to the South African geologist, that supports your idea that the Sun is a pulsar? And how can a pulsar form IF there is such a thing as neutron repulsion?>>
Ethelred
3.7 / 5 (3) Oct 08, 2011
How could degenerate matter form with that going on considering your contradictory claim that neutron repulsion makes Black Holes impossible despite the math not working for you at all? IF neutron repulsion stops Black Holes of all kinds forming no matter what the mass involved, as you have claimed many times, THEN the neutronium core of Neutron Stars CANNOT form due to that repulsion.

Since you are now claiming that neutron repulsion can blow galaxies apart how did they form in the first place since by neutron repulsion of that magnitude even stars WITH neutron stars in them could not for nor could they retain planets.

Please clear up these contradictions. Not a repost of the same papers that we are asking for elucidation on. An actual discussion of the evidence and the seemingly VERY serious contradictions in your claims about neutron repulsion.

Ethelred
Nanobanano
1 / 5 (3) Oct 08, 2011
I'd just like to point out that I'm not with Omatumr.

I came up with my thing about a year ago based on know facta about the Crab Nebula and Supernova, and by calculating the graviatational binding energy need to expode the "cloud" off the surface of the collapsing neutron star and leave it moving away at or above escape velocity for any given distance, r, from the center of mass.

I did this several different ways, and then relativized it for the fact that most of the energy is exhausted during the first SECOND of overcoming the surface gravity of the neutron star. I did the calculations for all of the ranges of estimated masses of the neutron star and cloud.

In all cases, this predicted the exact events and the exact calculated "missing mass" as ENERGY that was needed to overcome gravity.

Which is to say that roughly 1/3rd of the star's original mass was HAD TO BE annihilated in order to produce enough energy to eject the cloud. No other known process is strong enough.
Nanobanano
1 / 5 (2) Oct 08, 2011
Now the cloud has actually sped up it's expansion slightly over the past several centuries, because the explosions and radiations coming out of the star continue to push the gases out faster and faster.

HOWEVER, it was expanding at nearly the speed of light during the first fraction of a second as it blew up from the surface of the neutron star. Again, most of the kinetic energy was "wasted" just in overcoming gravity to get back up to about 1 stellar radius away from the center of mass, and by then, the cloud was only expanding slightly faster than escape velocity: essentially "coasting".
Nanobanano
1 / 5 (4) Oct 08, 2011
Ok, and here's a "negative" proof, in that I can prove that it had to be anti-matter by disproving it could have been some sort of Fusion related explosion.

1) Even if all of the mass of the Star has fused simultaneously to Neutronium, without a matter-antimatter annihilation event, AND you assume the shell was ejected from the Surface at ordinary stellar radius (i.e. solar radius)...there's actually not enough energy to explain that.

2) If an annihilation event did not happen, and all of this energy "somehow" came from Fusion only, then you have a problem, because the neutron star contains nowhere near enough neutronium by-product to explain the amount of energy that would have been needed to eject the nebula through Fusion only. Moreover, if there was 2, 5, 10 times as much neutronium and some of it was ejected, you also need to explain where the insane amount of energy came from which would have been needed to eject some of the neutronium...
Ethelred
3.7 / 5 (3) Oct 09, 2011
You are mistaking the neutron star that now exists for the supernova. The neutron star is the REMNANT of a Supernova. Most of the matter that was blown away did not have to escape from that deep in the gravity well.

HOWEVER, it was expanding at nearly the speed of light during the first fraction of a second as it blew up from the surface of the neutron star.
No. It is reasonably certain that the Crab is the result of a stellar collapse after the fuel ran out. There was NO neutron star until after the explosion.

Now since the historical records don't seem to have a clue as to what the progenitor star looked like no one can be sure if it really was a giant before the bang. However in standard models it should have been a pretty large star, thus most of the mass would have been at a large and some at a VERY large distance from the core. Very large as in over one AU though that far out it would more of a red hot vacuum than a photosphere.

Ethelred
omatumr
1 / 5 (7) Oct 09, 2011
There was NO neutron star until after the explosion.

Ethelred


Thanks for sharing your insight into the interior of stars !

Oops, today there seems to be NO constitution.

www.nytimes.com/2...emc=tha2

Regretfully,
Oliver K. Manuel
Ethelred
4.2 / 5 (5) Oct 09, 2011
The Constitution is not a suicide pact.

http://en.wikiped...ide_pact

"[a] strict observance of the written law is doubtless one of the high duties of a good citizen, but it is not the highest. The laws of necessity, of self-preservation, of saving our country when in danger, are of higher obligation. To lose our country by a scrupulous adherence to the written law, would be to lose the law itself, with life, liberty, property and all those who are enjoying them with us; thus absurdly sacrificing the ends to the means."[1]
Thomas Jefferson.

And you are not the sort of person that has any business sneering what others do to protect our nation. Or do you hate it that much?

Ethelred
MachinegunDojo
5 / 5 (5) Oct 09, 2011
I look forward to these articles and comments, I used to look forward to what omatumr would say when I initially found this place but now he's just a crazy loon that trolls and posts nothing relevant. You have a different point of view and I really like that, but you need to jump off the crazy train and put your brains where your mouth is.
Nanobanano
1 / 5 (2) Oct 09, 2011
Ethelred:

Obviously when a star is burning out it's fuel, you have higher and higher total density, and higher and higher mass per unit ratio in the fusion reactions, as you're fusing heavier and heavier elements.

So the metallic core of a star that is burnt out is going to be orders of magnitude more dense than the same mass star would be when it was first created.

Beryllium and Boron are 8 times as dense as hydrogen, yet by the time you get to the reactions involving and producing them you only get less than 1 Mev per reaction.

When you get to the CNO cycles you have even more density, but still less energy per reaction than the pure hydrogen reactions.

If density has increased then surface gravity is higher by default, and the reactions are giving much less energy per unit mass.

Oxygen is 18 times more dense than hydrogen, so by the time a Star is making Oxygen and heavier elements, the core is already collapsing.
Nanobanano
1 / 5 (1) Oct 09, 2011
There is no magical jump from one phase of this process to another, until you hit a critical limit.

We know from nuclear reactors on Earth, and from nuclear weapons test, that nuclear reactions are not "pretty". They don't just follow one chain until it runs out. They follow any available chain. Any reaction that can happen DOES happen.

The core of every star is always collapsing and increasing in density, until it hits it's limit, which is different depending on mass and composition.

As you increase the MASS of elements, more and more of the natter is NEUTRONS.

For example, a star with a lot of CNO in it's core would already be HALF NEUTRONS.

A star with a mostly Iron (or heavier elements) core would be over half neutrons already, and would already by over 50 times as dense as a "new" hydrogen star.

It's not like the "Neutron Star" core became pure neutronium over night.

And even if you took all of the remaining protons at that point...continued...
Nanobanano
1 / 5 (1) Oct 09, 2011
If you took all of the remaining protons at that point and fused them to neutronium (to within a geometric limit, since there's still going to be some stray protons somewhere in there,) the maximum amount of energy available through FUSION is still going to be hundreds of times smaller than the gravitational binding energy consistent with the "escape velocity" of the "surface" of an Iron core.

So simply fusing an iron core instantaneously to neutronium will not produce enough energy to eject the Crab Nebula at escape velocity (plus 1500km/s since it's actually accelerating instead of slowing down). it isn't even close to enough energy.
Nanobanano
1 / 5 (1) Oct 09, 2011
Although I find that given the calculations of the radius of the nebula, it would have actually had to average 1723km/s expansion rate for the past 957 years in order to reach the size it is now.

I'm sure Ghost of Otto, or some other nut job will complain because I actually checked the calculations and found them to be wrong. What else is new. No big deal eh? 1500, 1723, only off by nearly 20%.

Part of the problem with astronomy is the margin of error in distances and masses always seems to be as much as half as big as the measurement itself, and since gravity is proportional to mass, and inverse proportional to radius of an object, that makes a pretty damn big difference for distances to be off by 20% and mass to be off by 50%.
jsdarkdestruction
5 / 5 (1) Oct 09, 2011
I look forward to these articles and comments, I used to look forward to what omatumr would say when I initially found this place but now he's just a crazy loon that trolls and posts nothing relevant. You have a different point of view and I really like that, but you need to jump off the crazy train and put your brains where your mouth is.

google "oliver k manuel arrested" and look at what comes up.
Ethelred
3.7 / 5 (3) Oct 10, 2011
So the metallic core of a star that is burnt out is going to be orders of magnitude more dense than the same mass star would be when it was first created.
Well the star wasn't 'created' in the first place. After the helium starts burning the star has a very short remaining life. The next phases are EXTREMELY short.

So the metallic core of a star that is burnt out is going to be orders of magnitude more dense than the same mass star would be when it was first created.
In a stellar core? The density depends on the temperature and the requirements for the elements undergoing fusion.

If density has increased then surface gravity is higher by default,
No. You seem to be forgetting that stars get BIGGER in diameter when they leave the main sequence. Surface gravity drops. CORE gravity increases but because of the increase in temperature it the core does not get as dense as you seem to think.>>
Ethelred
3.7 / 5 (3) Oct 10, 2011
and the reactions are giving much less energy per unit mass.
But the rate of the reactions are much higher. H-H is a rare reaction. The rest go much faster. More energy is being produced. Take look at Betelgeuse.

the core is already collapsing.
Partial. The core shrinks as helium starts BUT hydrogen begins to fuse in a shell outside the core. This sequence continues each time the core reaches densities needed for a even heavier elements to fuse. Shell after shell with the lighter elements fusing as you go out from the core.

There is no magical jump from one phase of this process to another, until you hit a critical limit.
That limit is iron fusion. Won't happen in our Sun.

Any reaction that can happen DOES happen.
Yet only reactions that CAN happen do. Helium is not fusing in our Sun.

more and more of the natter is NEUTRONS.
Yes. But the stages after helium burning are very short.>>
Ethelred
3.7 / 5 (3) Oct 10, 2011
in it's core would already be HALF NEUTRONS
Actually that occurs when helium starts to fuse.

A star with a mostly Iron (or heavier elements) core would be over half neutrons already, and would already by over 50 times as dense as a "new" hydrogen star
That is the end. It lasts, what seconds, hours? Once iron begins to fuse the supernova starts, iron fusion releases most of it energy in neutrinos which take the energy out of the core and then the core collapses. Since iron IS dispersed in a supernova we know that it does not all become neutronium.

It's not like the "Neutron Star" core became pure neutronium over night
Correct. Its SECONDS. Iron flashes to neutronium and the star blows up. Only a fraction of the star's mass remains to form the neutron star.

If you took all of the remaining protons at that point
Any remaining in what is left of the core are compressed into neutronium except near the surface where there would be degenerate matter.>>
Ethelred
3.7 / 5 (3) Oct 10, 2011
he maximum amount of energy available through FUSION is still going to be hundreds of times smaller than the gravitational binding energy consistent with the "escape velocity" of the "surface" of an Iron core.
Sorry but like Marvin you missed the 'Earth shattering kaboom' stage. That happened BEFORE or rather OUTSIDE the core that forms the remnant.

So simply fusing an iron core instantaneously to neutronium will not produce enough energy to eject the Crab Nebula at escape velocity
Except that isn't how it happens. The iron fusion REMOVES energy from the core causing core collapse and the inner shells to fall as well until they hit the core and rebound. With the core blasting out a such a staggering number of neutrinos through the no longer falling outer shells the neutrinos actually interact with the highly dense and now rebounding matter and transferring sufficient energy to help drive the matter back out.>>
Ethelred
3.7 / 5 (3) Oct 10, 2011
All the elements heavier than iron are formed during this maximum pressure/density stage as the rebound begins.

http://en.wikiped...upernova

http://en.wikiped...upernova#Type_II

You are making calculations based on the matter being where it wasn't. If it isn't on the surface of the core, which it wasn't, then your calculations are wrong. No matter how well or badly you did them you started out wrong and thus GIGO.

Ethelred

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