Chapter 25: Beyond Our Solar System

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Across
  1. 3. a star that has exhausted most or all of its nuclear fuel and has collapsed to a very small size, believed to be near its final stage of evolution
  2. 8. the distance light travels in a year, about 9.5 trillion kilometers
  3. 9. one of two stars revolving around a common center of mass under their mutual gravitational attraction
  4. 10. a very large, very bright red giant star
  5. 12. a graph that shows the relationship between the temperature and luminosity of stars
  6. 15. the theory that proposes that the universe originated as a single mass, which subsequently exploded
  7. 17. a massive star star that has collapsed such a small volume that its gravity prevents the escape of everything, including light
  8. 19. a star that falls into the main-sequence category on the H-R diagram; This category contains the majority of stars and runs diagonally from the upper left to the lower right on the H-R diagram
  9. 20. a large, cool star of high luminosity; a star occupying the upper-right portion of the H-R diagram
Down
  1. 1. a variable radio source of small size that emits radio pulses in very regular periods
  2. 2. a star whose brightness varies periodically because it expands and contracts; a type of pulsating star
  3. 4. a system of galaxies containing from several thousands of member galaxies
  4. 5. an exploding star that increases in brightness many thousands of times
  5. 6. the brightness of a star when viewed
  6. 7. a collapsing cloud of gas and dust destined to become a star; a developing star not yet hot enough to engage in nuclear fusion
  7. 11. a group of stars, dust, and gases held together by gravity
  8. 12. a law that states that the galaxies are retreating from the Milky Way at a speed that is proportional to their distance
  9. 13. a star that explosively increases in brightness
  10. 14. a star of extremely high density composed entirely of neutrons
  11. 16. the apparent brightness of a star if it were viewed from a distance of 32.6 light-years; used to compare the true brightness of stars
  12. 18. an apparent group of stars originally named for mythical characters: The sky is presently divided into 88 constellations