Density wave
That makes sense, the density wave forming the arm is operating on the interstellar medium, and it's not surprising the arm extends into areas where the gas density can no longer support star formation.
Elisee Reclus
Space/Science » in reply to re: See also
That makes sense, the density wave forming the arm is operating on the interstellar medium, and it's not surprising the arm extends into areas where the gas density can no longer support star formation.
Elisee Reclus