If a collapsing object does not accumulate enough mass to trigger fusion, what might it become?

Answer

A brown dwarf

If the accumulating mass is insufficient to reach the 15 million Kelvin milestone for fusion, the object will cool down and fade away, potentially becoming a brown dwarf.

If a collapsing object does not accumulate enough mass to trigger fusion, what might it become?
star formationastrophysicsprotostarsstellar physicsheat generation