We point out that although conventional stars are primarily fed by burning of nuclear fuel at their cores , in a strict sense , the process of release of stored gravitational energy , known as , Kelvin - Helmholtz ( KH ) process is either also operational albeit at an arbitrary slow rate , or lying in wait to take over at the disruption of the nuclear channel .
In fact , the latter mode of energy release is the true feature of any self-gravity bound object including stars .
We also highlight the almost forgotten fact that Eddington was the first physicist to introduce Special Relativity into the problem and correctly insist that , actually , total energy stored in a star is not the mere Newtonian energy but the total mass energy ( E = Mc ^ { 2 } ) .
Accordingly , Eddington defined an “ Einstein Time Scale ” of Evolution where the maximum age of the Sun turned out to be t _ { E } \approx 1.4 \times 10 ^ { 13 } yr .
This concept has a fundamental importance though we know now that Sun in its present form can not survive for more than 10 billion years .
We extend this concept by introducing General Relativity and show that the minimum value of depletion of total mass-energy is t _ { E } = \infty not only for Sun but for and sufficiently massive or dense object .
We propose that this time scale be known in the name of “ Einstein - Eddington ” .
We also point out that , recently , it has been shown that as massive stars undergo continued collapse to become a Black Hole , first they become extremely relativistic Radiation Pressure Supported Stars .
And the life time of such relativistic radiation pressure supported compact stars is indeed dictated by this Einstein -Eddington time scale whose concept is formally developed here .
Since this observed time scale of this radiation pressure supported quasistatic state turns out to be infinite , such objects are called Eternally Collapsing Objects ( MECO ) .
Further since ECOs are expected to have strong intrinsic magnetic field , they are also known as “ Magnetospheric ECO ” or MECO .