« on: Yesterday at 09:55:06 »
Quote from: Petrochemicals
Well it only burns a third of its fuel, and apparently?That depends on how well the star's matter is mixed by convection.
The Sun only mixes the outer 30%, so a lot of hydrogen can be left-over without undergoing fusion.
However, smaller red dwarf stars are fully convective, so they can burn almost all their hydrogen fuel.
the proton is not a thermal 3nergy carrier ?In the Sun, the temperature is so high that protons and electrons (and helium nuclei) are separated into a plasma.
All of these in one patch of plasma are at the same temperature, which means that they have the same average kinetic energy. Because electrons are lighter than protons, they have a much higher velocity for the same kinetic energy.
But all of the components of the plasma (including the protons) carry thermal energy and participate in carrying it by convection, radiation and conduction into adjacent patches of plasma.
If the star where not emmitting as much energy as it produced within it, or conversley emmitted more than it preduced it's gravitational potential would have to changeIf we ignore stellar winds (which represent a slow loss of mass), then from a distance, the star would have a constant mass and a constant gravitational potential.
If you look more closely under the surface, you would see changes in temperature, pressure and size over time within a non-equilibrium star. But I don't see how it changes the gravitational potential. Do you mean the "surface gravity"?
according to that virial theoryThis is used to represent the movement of passive objects that interact loosely with each other, like the molecules in a gas, or the stars in a galaxy, or galaxies in the universe. It is not applicable in a strongly-interacting environment like a star which is generating heat by nuclear fusion.
You need a different kind of computer model to calculate the future of a galaxy compared to the future of an individual star (although knowledge gained from one simulation might result in tweaks to the other kind of simulation).
it is apparently very well known within astronomical circles to estimate masses and energies. That surely is an equilibriumYes, it is well known how to simulate these systems.
A gas in a closed vessel (no energy in, no energy out) can rapidly approach thermal equilibrium.
The orbits of stars in a galaxy could also reach an equilibrium after several galaxy rotations (a billion years or so) - provided you prevented collisions with other galaxies (or near misses), mergers of supermassive black holes, and other disruptive events that represent an injection or loss of energy.
The matter inside a star only reaches an equilibrium state after fusion stops (this represents an injection of energy) and if you prevented it radiating energy into space (this represents a loss of energy). In stars that aren't inside a Dyson sphere, this only happens when the star's temperature has dropped to almost absolute zero, from the surface right down to the core.
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