How to use in-sentence of “protostar”:
+ A protostar with less than 0.08 solar masses never reaches the 10 million K temperature needed for efficient hydrogen fusion.
+ So, as a protostar shrinks, its rate of spin increases.
+ As a protostar collapses it heats up because the gas particles run into each other.
+ The protostar is ‘born’ when it begins to emit enough energy to balance out its gravity and halt gravitational collapse.
+ This is a massive protostar about 300 times brighter than our Sun.
