Why Do the Spiral Arms Show Up So Clearly in Spiral

question 170

Multiple Choice

Why do the spiral arms show up so clearly in spiral galaxies?

• A) Stars are spread almost uniformly over the galaxy (outside the nuclear bulge), but the brightest stars occur only in the spiral arms, where their brightness and the fact that they illuminate gas clouds make the arms stand out.
• B) Stars are spread uniformly over the galaxy, but the dust forms a spiral pattern, absorbing starlight; the spiral arms are the dust-free regions between the dust lanes.
• C) The number of stars in the arms is several times larger than in the regions between, so these arms are reasonably distinct.
• D) Stars occur only in the spiral arms (and the nuclear bulge), with essentially none between the arms, so the arms show up very distinctly.

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Definitions:

Team's Cohesiveness

The degree to which members of a team are attracted to the team and motivated to remain part of it.

Task Cohesion

The degree to which group members work together in a coordinated way to achieve mutual goals.

Social Cohesion

The degree of interconnectedness and trust among members of a society, contributing to its stability and solidarity.

Collective Goals

Objectives or outcomes that are shared by members of a group, driving cooperation and collective action towards achieving these common ends.