Science Crossword puzzle

3. The birthplace of a star.
6. When hydrogen is converted into helium.
7. It is a dying star in the final stage of a stellar evolution.
10. Is a rotating circumstellar disk of dense gas surrounding a young newly formed star.
12. Extremely hot temperatures and pressure and generated once a supernova occurs.
15. The abundant element.
16. It is when Helium fused into Carbon. Known as the largest know star.
17. When it ran out of helium, it exploded, dispersing elements into space.
18. Expansion, not explosion.
20. The remains of a white dwarf.

1. In the core of stars, particularly during the later stages of their lives, nuclear fusion reaction occurs.
2. when Neutron and Protons combined.
4. It is formed by the death of a massive star or the collapse of interstellar gas.
5. a type of reaction is when the nuclei of two atoms merge as one.
8. Collection of tightly packed neutrons.
9. formed 4.5 billion years ago.
11. Formed from nebula due to the gravity that pulled hydrogen gas together until it spins faster.
13. ball of gas and plasma.
14. An infinitely small point of extremely high temperature and density.
19. It is after one second after the big bang, it's size grew large enough to form new and more massive type of particles.