What phenomenon is primarily responsible for the persistent appearance of spiral arms in a galactic disk?
Answer
Density waves propagating through the disk
The spiral structure is attributed to density waves moving through the galactic disk. As gas clouds enter these compressed regions, star formation is triggered, making the arms appear bright and defined temporarily.

#Videos
We Can't Explain Spiral Galaxies - The Winding Problem - YouTube
Related Questions
What are the three main morphological classes used to categorize galaxies?What phenomenon is primarily responsible for the persistent appearance of spiral arms in a galactic disk?Which characteristic fundamentally contrasts elliptical galaxies with spiral galaxies?How does an Sc type spiral galaxy differ from an Sa type galaxy according to sub-classification?Where is the majority of ongoing star formation typically concentrated within a spiral galaxy structure?What are the two primary scenarios cited for the origin of a galaxy classified as irregular?What characterizes the stellar population and gas content of a spiral galaxy's central bulge compared to its arms?What potential classification error can occur when observing a spiral galaxy edge-on?What evolutionary pathway can lead to a large, featureless elliptical galaxy from interacting spirals?Which statement accurately describes the Milky Way's galactic classification?