Who developed the Density Wave Theory to explain long-lived spiral structures?
Answer
C.C. Lin and Frank Shu
The resolution to the long-standing winding problem was provided in the mid-1960s by the work of C.C. Lin and Frank Shu. They formulated the Density Wave Theory, which shifted the understanding of spiral arms from fixed material structures to dynamic, large-scale density enhancements. This theory posits that the arms are quasi-stationary structures that propagate through the galactic disk at a speed independent of the orbiting matter. This breakthrough allowed astronomers to reconcile the persistence of spiral patterns with the mechanics of differential rotation present in galactic disks.
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