Spiral structure
A) rotates at the same speed as the gas in the disk.
B) rotates at a speed that is different than the gas in the disk.
C) stays constant in time as the gas in disk rotates through it.
D) None of the above is true.

Question

Quizplus · Accepted Answer

The spiral structure in galaxies is a density wave that rotates at a different speed than the gas and stars in the disk, allowing them to move through the spiral arms.

Spiral Structure