It depends on the age of the star http://en.wikipedia.org/wiki/Kelvin-Helmholtz_mechanism
Harry On Sun, Apr 27, 2014 at 12:00 PM, Jones Beene <[email protected]> wrote: > *From:* Daniel Rocha > > > > Its heat is probably due the remaining due its formation plus its slow > contractrion, That is, all its heat is about converting gravitational > energy into heat. > > > > Gravitational heating must surely provide a fraction of what is seen but > my guess is less than half. The contribution from gravity is a function of > mass and the age of the object, which we do not know for sure - and > accretion, if any. Gravitational heating would be minimal if the object > were as old as the solar system and with low accretion. An LLNL study of > planetary thermodynamics concluded gravitational heat contributes about > 7.5% of the total heat of Earth and the remnant heat from the original > formation is almost as much. > > > > The remaining 85%, at least on Earth, is concluded to be fueled by the > nuclear decay of radioactive isotopes including Potassium, Uranium and > Thorium and actual fission is possible. However, the study ignored LENR (as > expected). Even on earth, without metallic hydrogen, LENR cannot really be > ruled out as significantly contributory (once it is shown to be real) but > that assertion will await further proof. For now, it is ignorable. > > > > The error in a thermal accounting of a brown dwarf, since important > information on age and thermal history is lacking - is to assume that since > a mundane source (like gravitation heating) provides a significant fraction > of the internal heat, then there is no reason to look for other large > contributions. > > > > >
