Across
- 3. Long, spiral pattern of bright stars, star clusters, gas, and dust that extends from the center to the edge of the disk of spiral galaxies
- 6. 1000 parsecs, about 3300 ly.
- 7. The low-density extension of the halo of a galaxy; now suspected to extend many times the visible diameter of the galaxy
- 9. have bold, symmetric two-armed patterns
- 12. The spherical region of a spiral galaxycentralbulge
- 14. A graph of orbital velocity versus radius in the disk of a galaxy
- 15. Orbital motion in accord with Kepler’s laws of planetary motion
- 16. meaning “woolly”
Down
- 1. The conjecture that spiral arms in disk galaxies are caused by a pressure wave that rotates slowly around the galaxy, triggering star formation by compressing interstellar gas clouds
- 2. The process by which the birth of stars compresses the surrounding gas clouds and triggers the formation of more stars; proposed to explain spiral arms
- 4. All material confined to the plane of the galaxy. The spheroidal cloud of stars at the center of most spiral galaxies, including our Milky Way Galaxysphericalcomponent The part of the galaxy including all matter in a spherical distribution around t A graph of orbital velocity versus radius in the disk of a galaxy.
- 5. standard light sources that astronomers could use to find distances
- 8. Object used to map the spiral arms, for example O and B associations, open clusters, clouds of ionized hydrogen, and some types of variable stars.
- 10. Nonluminous material that is detected only by its gravitational influence
- 11. The part of the galaxy including all matter in a spherical distribution around the center
- 13. The spheroidal cloud of stars at the center of most spiral galaxies, including our Milky Way Galaxy