The Disks of Spiral Galaxies Appear Blue Because

question 74

Multiple Choice

The disks of spiral galaxies appear blue because:

• A) they are moving toward us
• B) they contain a relatively high concentration of low-mass stars
• C) they contain active regions of star formation
• D) they contain more metals that, when ionized, emit blue light
• E) stars collide with each other frequently in these dense regions and explode as Type I supernovae

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Definitions:

Variable Pitch

Referring to the capability of adjusting the angle or pitch of blades in fans, propellers, or turbines to control performance.

Impeller

The driving member of a torque converter torus; the impeller is mechanically connected to the engine crankshaft and should rotate at the same speed.