Ch. 17-19 Key Terms

123456789101112131415161718192021222324252627
Across
  1. 5. a plot of luminosity against surface temperature (or spectral type) for a group of stars
  2. 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
  3. 7. a star of exaggerated size with a large, extended photosphere
  4. 11. an empirical relation between the periods and luminosities of certain variable stars
  5. 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
  6. 16. motion toward or away from the observer; the component of relative velocity that lies in the line of sight
  7. 20. one of a class of giant pulsating stars with periods shorter than 1 day, useful for finding distances
  8. 22. the rate at which a star or other object emits electromagnetic energy into space; the total power output of an object
  9. 25. the angular change per year in the direction of a star as seen from the Sun
  10. 26. the observed relation between the masses and luminosities of many (90% of all) stars
  11. 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. 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. 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. 3. the total (three-dimensional) speed and direction with which an object is moving through space relative to the Sun
  4. 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
  5. 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
  6. 9. a variable star that pulsates in size and luminosity
  7. 10. a binary star in which the two components are telescopically resolved
  8. 13. an apparent displacement of a nearby star that results from the motion of Earth around the Sun
  9. 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
  10. 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
  11. 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
  12. 18. the selection of sample data in a nonrandom way, causing the sample data to be unrepresentative of the entire data set
  13. 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
  14. 21. two stars that revolve about each other
  15. 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
  16. 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