What does the equivalent of an H-R diagram for galaxies, plotting ...

[genevieve1028]

What does the equivalent of an H-R diagram for galaxies, plotting luminosity versus color, show?
 
  A) galaxies fill the diagram showing that there is no correlation between luminosity and color
  B) two clumps, one blue with relatively low luminosity, one red with relatively high luminosity, and a valley in between with few galaxies
  C) a continuum from faint, blue galaxies to bright, red galaxies
  D) a continuum from faint, red galaxies to bright, blue galaxies
  E) a main sequence, just as for stars

Question 2

The spiral structure of the Milky Way is best revealed by ________ cm radio observations of hydrogen atoms.
 
  Fill in the blank(s) with correct word

[akudia]

Answer to Question 1

B

Answer to Question 2

21

[genevieve1028]

Thank you!

[akudia]

Always glad to help...