Across
- 5. a plot of luminosity against surface temperature (or spectral type) for a group of stars
- 6. a star that belongs to a class of yellow supergiant pulsating stars; these stars vary periodically in brightness, and the relationship between their periods and luminosities is useful in deriving distances to them
- 7. a star of exaggerated size with a large, extended photosphere
- 11. an empirical relation between the periods and luminosities of certain variable stars
- 12. a sequence of stars on the Hertzsprung–Russell diagram, containing the majority of stars, that runs diagonally from the upper left to the lower right
- 16. motion toward or away from the observer; the component of relative velocity that lies in the line of sight
- 20. one of a class of giant pulsating stars with periods shorter than 1 day, useful for finding distances
- 22. the rate at which a star or other object emits electromagnetic energy into space; the total power output of an object
- 25. the angular change per year in the direction of a star as seen from the Sun
- 26. the observed relation between the masses and luminosities of many (90% of all) stars
- 27. a binary star in which the plane of revolution of the two stars is nearly edge-on to our line of sight, so that the light of one star is periodically diminished by the other passing in front of it
Down
- 1. a measure of the amount of light received by Earth from a star or other object—that is, how bright an object appears in the sky, as contrasted with its luminosity
- 2. the classification of stars according to their temperatures using the characteristics of their spectra; the types are O, B, A, F, G, K, and M with L, T, and Y added recently for cooler star-like objects that recent survey have revealed
- 3. the total (three-dimensional) speed and direction with which an object is moving through space relative to the Sun
- 4. a graph that displays the time variation of the light from a variable or eclipsing binary star or, more generally, from any other object whose radiation output changes with time
- 8. a low-mass star that has exhausted most or all of its nuclear fuel and has collapsed to a very small size; such a star is near its final state of life
- 9. a variable star that pulsates in size and luminosity
- 10. a binary star in which the two components are telescopically resolved
- 13. an apparent displacement of a nearby star that results from the motion of Earth around the Sun
- 14. a binary star in which the components are not resolved but whose binary nature is indicated by periodic variations in radial velocity, indicating orbital motion
- 15. a unit of distance in astronomy, equal to 3.26 light-years; at a distance of 1 parsec, a star has a parallax of 1 arcsecond
- 17. an object intermediate in size between a planet and a star; the approximate mass range is from about 1/100 of the mass of the Sun up to the lower mass limit for self-sustaining nuclear reactions, which is about 0.075 the mass of the Sun; brown dwarfs are capable of deuterium fusion, but not hydrogen fusion
- 18. the selection of sample data in a nonrandom way, causing the sample data to be unrepresentative of the entire data set
- 19. a classification of a star according to its luminosity within a given spectral class; our Sun, a G2V star, has luminosity class V, for example
- 21. two stars that revolve about each other
- 23. an older system of measuring the amount of light we receive from a star or other luminous object; the larger the magnitude, the less radiation we receive from the object
- 24. difference between the magnitudes of a star or other object measured in light of two different spectral regions—for example, blue minus visual (B–V) magnitudes