Question

the life cycle of a star
protostar
main - sequence star
supergiant
supernova
black dwarf
neutron star
increasing time
increasing mass
draggables
white dwarf
nebula
black hole
red giant

Explanation:

Stars begin as nebulae which collapse to form protostars. A protostar evolves into a main - sequence star. Depending on mass, a main - sequence star can become a red giant (low - mass stars) which then becomes a white dwarf and eventually a black dwarf. High - mass main - sequence stars become supergiants, then supernovae, which can form either neutron stars or black holes.

Answer:

Top - to - bottom, left - to - right: Nebula; Red giant; White dwarf; Black hole