The contraction of a star under gravity, the potential energy thus lost being converted into heat and radiated away. The Helmholtz–Kelvin contraction time-scale is defined as the time it would take for a star to collapse if nuclear burning were switched off and it continued to radiate at the same luminosity. For the Sun this time would be about 30 million years. It is named after the German scientist Hermann Ludwig Ferdinand von Helmholtz (1821–94) and Lord Kelvin.
Subjects: Astronomy and Astrophysics.