This line of reasoning underlies an exciting new theory of spiral-galaxy structure. A computer simulation based on this theory has reproduced the appearance of many spiral galaxies without assuming an underlying density wave, the hallmark of the most widely accepted theory of the large-scale structure of spiral galaxies. That theory maintains that a density wave of spiral form sweeps through the central plane of a galaxy, compressing clouds of gas and dust, which collapse into stars that form a spiral pattern.
16.1. The primary purpose of the passage is to
describe what results when a supernova triggers the creation of chains of star-forming regions
propose a modification in the most widely accepted theory of spiral-galaxy structure
compare and contrast the roles of clouds of gas and dust in two theories of spiral-galaxy structure
describe a new theory of spiral-galaxy structure and contrast it with the most widely accepted theory
describe a new theory of spiral-galaxy structure and discuss a reason why it is inferior to the most widely accepted theory
16.2. The passage implies that, according to the new theory of spiral-galaxy structure, a spiral galaxy can be created by supernovas when the supernovas are
producing an underlying density wave
affected by a density wave of spiral form
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