Stars

5. a ring-shaped nebula formed by an expanding shell of gas around an aging star.
7. a star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.
9. a very large star of high luminosity and low surface temperature
10. a small very dense star that is typically the size of a planet

1. stars with a supergiant luminosity class
2. a region of space having a gravitational field so intense that no matter or radiation can escape.
3. Any star which is larger than eight solar masses during its regular main sequence lifetime is considered a
4. a star with an initial mass of 0.5 to 8 times that of Earth's sun
6. a cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter
8. very high density, composed predominantly of closely packed neutrons