Stars

2. the distance at which an object has a parallax of one arc
4. an apparent change in position caused by motion of the observer
11. group of stars that forms a pattern in the sky
12. brightness an object would have if it were placed at a distance of 10 pc
14. energy output from the surface of a star per second, measured in watts
15. relatively cool, dark spots appearing on the surface of the photosphere
16. a nuclear reaction in which lightweight nuclei combine into heavier nuclei
17. a sudden eruption of particles and radiation from the surface of the Sun
18. top layers of the Sun’s atmosphere
19. small, extremely dense remnant of a star whose gravity is so immense that not even light can escape its gravity field

1. a cloud of interstellar dust or gas or both, which collapses on itself as a result of its own gravity
3. massive explosion that occurs when the outer layers of a star are blown off
5. ancient Greek classification system based on how bright a star appears to be
6. two stars gravitationally bound together and orbiting about a common center of mass
7. a nuclear reaction in which an atomic nucleus splits into smaller, lighter nuclei releasing energy
8. a stream of high-speed, ionized particles flowing outward through the solar system from the Sun's corona
9. the hot, condensed, disk-shaped object at the center of a collapsing cloud
10. collapsed, dense core of a star that forms quickly while its outer layers are falling inward
13. a spinning neutron star that exhibits a pulsing pattern massive