Careful measurements reveal that a star maintains a steady apparent brightness at most times, except ...

Careful measurements reveal that a star maintains a steady apparent brightness at most times, except that at precise intervals of 93 hours. the star becomes dimmer for about 2 hours. The most likely explanation for this is that the star ________.
 
  a. has a very large sunspot on its surface
 b. is a member of an eclipsing binary star system
 c. is a white dwarf
 d. is a Cepheid variable
 e. is periodically ejecting gas into space, every 93 hours

Question 2

Astronomers consider the Solar System's Kuiper belt extending beyond the orbit of Neptune as an example of an old debris disk.
 
  a. True
  b. False
  Indicate whether the statement is true or false

Question 3

The Hertzsprung-Russell diagram can be labeled many different ways. Which coordinates CANNOT be used on an H-R diagram?
 
  a. luminosity versus spectral type
 b. luminosity versus temperature
 c. radius versus temperature
 d. absolute magnitude versus temperature
  e. luminosity versus color

Question 4

Kuiper belt objects appear to be ancient planetesimals that formed in the outer Solar System but were never incorporated into a planet.
 
  a. True
  b. False
  Indicate whether the statement is true or false

Question 5

The classification of stellar spectra started with the amount of hydrogen in the star's spectrum; however, now a better scheme uses the star's _____.
 
  a. mass
 b. diameter
 c. radius
 d. temperature
  e. luminosity