What temperature must the core of a protostar reach to begin sustained thermonuclear fusion?

Answer

Around 10 million Kelvin

The transition to the main sequence occurs when gravitational contraction raises the core temperature and pressure high enough, specifically around 10 million Kelvin, to ignite sustained hydrogen fusion.

What temperature must the core of a protostar reach to begin sustained thermonuclear fusion?
protostarstellar evolutionstar formationastrophysics