Across
- 5. A cluster of up to several thousand stars, found only in the disks of galaxies and often contain young stars
- 8. Stars that appear just below the supergiants on the H-R diagram because they are somewhat smaller in radius and lower in luminosity
- 9. A system for describing stellar brightness by using numbers
- 10. A measure of the apparent brightness of an object in the sky, based on the ancient system developed by Hipparchus
- 14. The length of time for which a star of a particular mass can shine by fusing hydrogen into helium in its core
- 16. A measure of an object's luminosity; defined to be the apparent magnitude the object would have if it were located exactly 10 parsecs away
- 17. The hot, compact corpses of low-mass stars, typically with a mass similar to that of the Sun compressed to a volume the size of Earth
- 18. The total power output of an object, usually measured in watts or in units of solar luminosities
- 19. Stars whose temperature and luminosity place them on the main sequence of the H-R diagram
- 20. The point on a cluster's H-R diagram where its stars turn off from the main sequence; the age of the cluster is equal to the main-sequence lifetime of stars at the main-sequence turnoff point
Down
- 1. A star system that contains two stars
- 2. A binary star system in which both stars can be resolved through a telescope
- 3. A spherically shaped cluster of up to a million or more stars; found primarily in the halos of galaxies and contain only very old stars
- 4. A way of classifying a star by the lines that appear in its spectrum
- 6. The distance to an object with a parallax angle of 1 arcsecond; approximately equal to 3.26 light-years
- 7. A binary star system in which the two stars happen to be orbiting in the plane of our line of sight, so that each star will periodically eclipse the other
- 11. The amount of light reaching us per unit area from a luminous object
- 12. Stars that grow alternately brighter and dimmer as their outer layers expand and contract in size
- 13. A star that is between being a main-sequence star and being a giant; subgiants have inert helium cores and hydrogen-fusing shells
- 15. A binary star system whose binary nature is revealed because we detect the spectral lines of one or both stars alternately becoming blueshifted and redshifted as the stars orbit each other