Question

protostar
gravitational collapse
star
protoplanetary disk
nebula
an extremely hot, dense celestial object with high enough core temperature and pressure for hydrogen atoms to fuse into helium atoms
a large, cloud - like structure in space—mostly made of gas and dust—from which stars can form
the inward contraction of a cloud of gas and dust as it gets more massive and its gravity increases
a hot, dense celestial object formed when a cloud of gas and dust collapses in on itself due to gravity
a flattened, rotating cloud of gas and dust surrounding a newly formed star, from which comets, asteroids, and planets can form

Explanation:

Match each term to its definition based on stellar formation processes:

1. The definition describes an object with hydrogen fusion in its core, which is a star.
2. A large gas/dust cloud that forms stars is a nebula.
3. Inward contraction of a gas/dust cloud due to gravity is gravitational collapse.
4. A hot dense object from collapsed gas/dust (before fusion starts) is a protostar.
5. A flattened disk around a new star that forms planets is a protoplanetary disk.

Answer:

1. star: An extremely hot, dense celestial object with high enough core temperature and pressure for hydrogen atoms to fuse into helium atoms
2. nebula: A large, cloud-like structure in space—mostly made of gas and dust—from which stars can form
3. gravitational collapse: The inward contraction of a cloud of gas and dust as it gets more massive and its gravity increases
4. protostar: A hot, dense celestial object formed when a cloud of gas and dust collapses in on itself due to gravity
5. protoplanetary disk: A flattened, rotating cloud of gas and dust surrounding a newly formed star, from which comets, asteroids, and planets can form