Which of the following can't be associated with the spiral arms of a galaxy?
a. dust and gas
b. metal-poor stars
c. young, massive stars
d. star formation
Question 2
The lower edge of the main-sequence band is known as ________ and represents the location in the H-R diagram at which stars begin their lives as main-sequence stars.
a. the Coulomb barrier
b. hydrostatic equilibrium
c. the birth line
d. the zero-age main sequence
e. the evolutionary track
