How do absorption lines from interstellar gas compare to absorption lines from stars?
A)They are wider than the lines from stars because the gas is hotter than most stars.
B)They are narrower than the lines from stars because the gas has a lower pressure than stars.
C)They indicate that the interstellar medium contains different elements than stars do.
D)They indicate that interstellar medium clouds have high velocities.

Question

Quizplus · Accepted Answer

Absorption lines from interstellar gas are narrower than the lines from stars because the gas has a lower pressure than stars. The pressure broadening effect is less pronounced in interstellar gas, resulting in narrower lines.

How Do Absorption Lines from Interstellar Gas Compare to Absorption