Star Life Cycle Crossword Puzzle

2. a celestial object of very small radius (typically 18 miles/30 km) and very high density, composed predominantly of closely packed neutrons.
4. the explosion of a massive star that has reached the end of its life and results in a brilliant burst of light.
5. stars that fuse hydrogen atoms to form helium atoms in their cores. Stable period of a star's life cycle.
9. a region of space having a gravitational field so intense that no matter or radiation can escape.
11. what stars like the Sun become after they have exhausted their nuclear fuel.
12. the force that attracts a body toward the center of the earth, or toward any other physical body having mass.
13. a cloud of dust and gas

1. what a white dwarf becomes when it has cooled sufficiently to no longer emit significant heat or light
3. They form when a star runs out of hydrogen fuel in their core, begins collapsing, and then outer shells of hydrogen around the core get hot enough to begin fusion. It expands and becomes the largest type of stars in the universe.
6. when a medium star like our own sun turns into ; it expands and engulfs the inner planets
7. a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
8. a contracting mass of gas which represents an early stage in the formation of a star, before nuclear fusion has begun.
10. the reaction in which two atoms of hydrogen combine together, or fuse, to form an atom of helium