For a star similar to the Sun, what is the approximate duration of the slow contraction stage before fusion takes over?
Answer
50 million years
While the initial collapse can be quick, the subsequent protracted slow contraction stage, where thermal pressure builds toward the fusion threshold, can last for approximately 50 million years for a solar-mass object.

Frequently Asked Questions
What period defines the time between initial gravitational collapse and the onset of stable nuclear fusion?What energy conversion is fundamental during the initial rapid gravitational collapse?Why does the initial collapse proceed unimpeded by thermal pressure in the very early stages?What mechanism allows a protostar to achieve a temporary, intermediate equilibrium before fusion begins?What physical change causes the free-fall contraction to slow dramatically into the Kelvin-Helmholtz phase?What role does material opacity play in accelerating internal heat buildup?What is the critical temperature required for hydrogen nuclei to overcome electrostatic repulsion and initiate fusion in a Sun-like star?Before fusion dominates, what mechanism supplies the energy output of a contracting protostar?Which characteristic activity distinguishes the turbulent protostar stage from a stable main-sequence star?For a star similar to the Sun, what is the approximate duration of the slow contraction stage before fusion takes over?