What caused the interstellar cloud to collapse?

Answer 1

Nebulae are massive collections of gas and dust that usually are very cool around 5-30 kelvin. These nebulae are the remains of dead stars that have long died and have had enough time to cool themselves from the original energy release of the nova or supernova that created them. As the nebula cools the particles begin to slow down and once cool enough gravity will begin to collapse the nebulae and form what is known as a protostar. This is the birth of stars, and is essential for star formation.

Answer 2

Gravity is the key.

Answer 3

it was to heavy

Answer 4

A "protostar" is the answer , I think.

Answer 5

Gravity.