The luminosity of a Seyfert galaxy varies with a regular period of months or years.

The luminosity of a Seyfert galaxy varies with a regular period of months or years.
 
  a. True
  b. False
  Indicate whether the statement is true or false

Question 2

A continuous spectrum is created by a hot ionized gas.
 
  a. True
  b. False
  Indicate whether the statement is true or false

Question 3

The broad emission lines of Seyfert galaxies imply high gas speeds in the nucleus.
 
  a. True
  b. False
  Indicate whether the statement is true or false

Question 4

If absorption lines of sodium are not present in a star's spectrum, the star must not contain any sodium.
 
  a. True
  b. False
  Indicate whether the statement is true or false