Across
- 3. starlike objects with emission lines in their spectra
- 7. weak radiation that is left over from the early, hot stages of the Big Bang expansion of the universe
- 10. are located in the giant branch of the Hertzsprung-Russell diagram, and pulsate in brightness because of the expansion and contraction of their outer layers
- 11. are found in the halo and bulge and contain even smaller traces of heavy elements
- 13. larger groups of clustered galaxies
- 14. stars with pulsation periods ranging from 1 to 100 days and varying luminosities
- 16. very bright, often giant, elliptical galaxy that emits as much or more energy in the form of radio wavelengths of visible light
Down
- 1. a galaxy's core in which highly energetic objects or activities are located
- 2. are found in the disk and arms and have small amounts of heavy elements
- 4. spiral regions of alternating density which rotates as a rigid pattern
- 5. stars with pulsation periods ranging from 1.5 hours to 1.2 days, generally having the same luminosity, regardless of pulsation period length
- 6. theory that proposes that the universe began as a single point and has been expanding ever since
- 8. value (H) used to calculate the rate at which the universe is expanding; measured in kilometers per second per megaparsec
- 9. thought to be made up of a form of subatomic particle that interacts only weakly with other matter
- 12. study of the universe-its nature, origin, and evolution
- 15. a spherical region where globular clusters are located