What is the physical process that spiral arms cause in interstellar gas and dust?

Answer

They are density waves that squeeze matter, triggering star formation.

Spiral arms are defined as density waves propagating through the galactic disk, squeezing interstellar gas and dust, which triggers star formation.

What is the physical process that spiral arms cause in interstellar gas and dust?

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Which Spiral Arm Of The Galaxy Is Ours? - YouTube

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