Posted: Tue Jan 10, 2017 7:03 pm
jarek wrote:..... and then small blue text on the bottom says that Eganowa analysis says that surprisingly the amount of energy generated by star decreases with increase of temperature of the core, what is consistent with his theory of electron assisted fusion (he calls it 'molecular mechanism of nuclear synthesis') (?)....
Other elements may be significant, but that Stars put out less energy (per unit volume/ density is well understood and reasonable with current understanding.
A star's core temperature is a straight forward application of the gas law. The core heats up[ through gravitational collapse till the gas outward pressure equals the inward pressure due to gravity. As the core losses heat through convection and radiation to the outer layers of the star and finally into space the core cools and the gravitational pressure becomes dominate and the star/ core shrinks further till a new balance is reached. Except, with fusion as a heat source you do not need to use additional gravitational potential energy to keep the core hot and in pressure equalibrium. The star is stable- in the so called main sequence phase of stellar evolution.
Things change as the star core starts running out of hydrogen, to maintain the pressure equilibrium against gravity it shrinks some and heats up till helium can start burning via the tri alpha process. As the helium burns up heavier produced elements start burning , like carbon,etc. All of these derivative reactions require higher temperatures, the core shrinks and becomes hotter- simplistically the gravity heats up the core and fusion maintains the temperature once reached. Each of these fusion steps produce less energy per reaction, as is obvious via the nuclear binding energy curve. At Ni62 there is a balance point, reactions just lighter than this produce relatively little energy compared to hydrogen- hydrogen fusion. Past Ni62 energy is actually absorbed with fusion.
As the star burns and sequentially burns up the lighter elements, each set of fusion reactions produce less energy per reaction. Because of this, to maintain the core pressure against gravity, the fuel needs to burn faster- which it will as the temperature increases. This is why a star can burn hydrogen for ages , but as it eats through the produced heavier elements the star ages faster, till it runs out of energy producing fusion fuels or the gravitational pressure cannot heat the core any further- to the degree necessary for the heavier element fusion to continue . Further considerations about the stars mass, and end of life physics then makes things further interesting.
The P-P reaction starts with two protons fusing with an electron also incorporated and (I think) a neutrino involved. This produces some energy, but it is important to remember that this is only the start of the P-P process and is the rate limiting step. Once the deuterium is made, it very quickly reacts with further protons or another deuterium to eventually produce helium4. This releases a lot of energy . Also, keep in mind that there is an alternate pathway. The CNO cycle. This takes a little higher temperature to surpass the P-P process. In the Sun it accounts for about 10% of the fusion output. In a larger star with greater inward gravitational pressure the core heats up and the CNO cycle becomes the dominate source of fusion energy (at least in metal rich stars). The CNO fusion cross section curve is much steeper than the P-P reaction curve. Thus, with a modest increase in core temperature, an exponential increase in the hydrogen fusion rate occurs. This is why a star with many times the mass of the Sun, has a core temperature only mildly greater- perhaps 30 million degrees. This is well below the ~ 100 million degree temperatures required for the tri alpha process of helium4 burning to contribute. The core size/ volume and thus the amount of fusion necessary to maintain a balance may be much greater but the temperature within that core is only mildly increased. This is why larger higher mass stars burn through their hydrogen supply faster, despite starting with initially larger supplies.
Stellar dynamics and evolution is a rich field of study. I hope this few snippets illustrates the need for caution when taking simple small claims as meaningful. They may be true but are taken out of context.
As for the electrons magnetic moment contributing , I have little understanding. But, that has never stopped me before! The key point may be the orientation of the electron spin and thus the direction of the magnetic moment. The electron may be moving in or out and have transverse motions as well. The balance of forces will depend on the sum of these motions. In cooler conditions- non ionized atoms, the electrons are paired up with one up and one down spin so the net effect is grossly zero. I use the word grossly as supple imbalances plases a role in atom behavior and molecular bondine etc. The field of spintronics is seeking to utilize these processes to add to the utility of systems, as compared to the traditional electrical interactions. If this may have a role in behavior in the harsh and extremely dynamic area of plasmas is intriging. But, consider that the electromagnetic force is a combination of electrical and magnetic properties. It is already incorperated in the electromagnetic force that governs Coulomb attraction and repulsion.