Across
- 1. variables: pulsation periods between 1 and 100 days.
- 3. arms: follows an orbital path around the nuclear center as shown.
- 5. bulge: center of galaxy.
- 6. black hole: begins with collapse of a dense gas cloud
- 10. star: the distance to the clusters by identifying variable stars.
- 12. a spherical region where globular clusters are located.
- 13. distance light travels in a year.
Down
- 2. 1: in the disk and arms and have small amounts of heavy elements.
- 4. variable: stars that have periods of pulsation between 1.5 hours and 1.2 days.
- 7. 2: found in the Halo and bulge and contain even smaller traces of heavy elements.
- 8. density: spiral regions of altemating density
- 9. any of the very large groups of stars and associated matter found throughout the universe.
- 11. distance from earth to sun.