Let me help you sort this out. Here is a recent telephoto taken at Mt. Palomar tentatively identifying an accumulating gas mass thought to be in a very primitive stage and just beginning to show the Ranque effect...
Posted on 10/06/2004 8:44:49 AM PDT by -=[_Super_Secret_Agent_]=-
Doesn't a star that goes nova do exactly that? Forgive my ignorance if this is compeltely wrong.
The Unknown Comic's impersonation of the first man to land on the sun:
[Jumping around...] "AAAAAAAAHHH! AAAAH! AAAAAAHHH!!"
I liked it better when they specified degrees Kelvin, but do recognize the change. To say "273 Kelvin" doesn't do as much for me as saying "273 degrees Kelvin", which is still cold.
Actually, the existence of different neutrino "flavors" was an experimental discovery, back in 1962. Schwartz, Steinberger and Lederman received the 1988 Nobel Prize for it.
As for the missing solar neutrinos, that problem was solved in the last few years by the Sudbury Neutrino Observatory. As expected, the answer was that the electron-type neutrinos coming out of the sun oscillate into muon- and tau-type neutrinos. Previous solar neutrino detectors were only sensitive to electron-type neutrinos, whereas SNO can detect all three.
I was focusing more on the first part - The 13th CGPM (1967) adopted the name kelvin (symbol K) instead of "degree Kelvin." I included the rest for completeness.
Well, no. Novas aren't powered by gravitational collapse, and they don't dissipate the entire star. Supernovas are powered by gravitational collapse, but they also don't dissipate the entire star, but leave a neutron star behind.
Or a black hole depending on the stellar mass.
Let me help you sort this out. Here is a recent telephoto taken at Mt. Palomar tentatively identifying an accumulating gas mass thought to be in a very primitive stage and just beginning to show the Ranque effect...
Thank you. I am, of course, still partially confused. It appears the author advances that idea that, given a gravity well where hydrogen is continually compressiing, the heat generated would produce expansive forces that outweigh the attraction of gravity. I am unsure if this threshold is below what is needed for fusion, or above it. However, even if above (hotter) than the fusion threshold, ultimately there comes a point where the heat (expansive) certainly exceeds the gravity, no? Thus, supernova? I am aware that every nova or supernova leaves behind a mass, even a singularity, but I cannot see how this situation does not agree with what this author is stating. Please try to assume I am a stupid person and explain again, if you have the time/inclination. This is fascinating to me. Now I must go pound some square blocks into round holes.
Unnngh Alert
The 'solution' above is known in the scientific community as a Theory. A Theory can fit the math, and be totally wrong.
Just ask the world's smartest quadriplegic.
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Yes, but not as hot as the new Mrs. Tiger Woods.
This I knew about.
"As for the missing solar neutrinos, that problem was solved in the last few years by the Sudbury Neutrino Observatory. As expected, the answer was that the electron-type neutrinos coming out of the sun oscillate into muon- and tau-type neutrinos. Previous solar neutrino detectors were only sensitive to electron-type neutrinos, whereas SNO can detect all three."
And this I didn't. EXPERIMENTAL DATA RULES!!!! All the mathematical hand-waving in the world is useless, without experimental verification (which is also why I don't believe in global warming---the best experimental data we have says it isn't happening).
This Bosco Renzoli feller must be real smart. Of course it's cold in there. You can't get any light in under all that other stuff, can you?
Bozo Ronscoli will be the next Ralph Sansbury!
I think the more intriguing question is why those hydrogen gang members picked the street corners we now find them on to hang out.
Gotta be cold in there. All the sunlight is going in the other direction. It's all so obvious!
Fifty years from now, people will look back at pictures like that and ask, "Look at those shoes! What were they thinking? "
The point is that the gravitation is the source of energy for the compression, which is the source of energy for the heat/pressure, which is the source of energy trying to make the gas expand..... you can't end up with more energy in the form of heat/pressure to "overcome" the force of gravity, because gravity is the ONLY source of energy in the process (contracting gas cloud) being described. For it to be otherwise would consitute a violation of conservation of energy.
Any cloud of material undergoing gravitational contraction eventually reaches an equilibrium point at which the internal pressure is exactly balanced against the gravitational forces trying to contract the cloud. The more massive the cloud, the higher the density is before equilibrium is reached. If the cloud is massive enough, the internal conditions eventually reach sufficient pressure and temperature to initiate nuclear fusion reactions, which in turn, provide a new source of heat (and radiation pressure), which stops the cloud (now star) from collapsing further.
And what happens when the star uses up the material able to fuse in the fusion regions in the stars interior? The fusion process starts to shut down, and energy and radiation pressure drop, so the star starts to contract again, further raising internal pressure and temperature, until eventually it is hot enough and dense enough for heavier nuclei to start to fuse, and a new round of fusion reactions, much more powerful than the hydrogen fusion process that preceeded it, and thus the higher energy and radiation pressure causes the star to expand again but to a much larger diameter than previously. This is the so-called "red giant" phase that occurs at the end of a star's life cycle.
This cycle repeats with ever heavier nuclei fusing and ever higher rates at ever higher pressures and temperatures, and the star get bigger and bigger..... until the material in the core has been fused into iron nuclei, at which point the reaction process stops, the now enormous star once again undergoes gravitational collapse as there is no longer any process left by which to generate enough energy in the core to stop it.
If the star is less than about 1.4 solar masses, it eventually finds an equilibrium state in which the pressure of the gases exactly balance the gravitational forces, but no nuclear reactions are possible, and the star simply cools off as it radiates it energy away, fading away as a dwarf star.
If the mass is more than 1.4 solar masses, but less than about 4 solar masses, the internal gravitational forces increase faster than the gas pressure can resist it, and the star cannot find an equilibrium state while the matter is still a gas. This results in the formation of a neutron star, where finally equilibrium is once again restored, but at a vastly smaller diamater than the original star.
And if the star is greater than about 4 solar masses, not even the neutron state can provide enough resistance to find an equilibrium in which the gravitational force is balanced, and the star collapses until the outer, hydrogen rich regions are compressed ALL AT ONCE to the fusion flash point, resulting in a supernova explosion of the outer regions of the star. If what remains is less than 4 solar masses, a neutron star may result, if larger than 4 solar masses, the remaining matter undergoes final, complete gravitational collapse for which there is no known force powerful enough to resist the increasing gravitational forces, and a black hole is the result.
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