What Useful Purpose Did RR Lyrae Stars Serve for Harlow

question 62

Multiple Choice

What useful purpose did RR Lyrae stars serve for Harlow Shapley in locating the galactic center?

• A) Their brightness variations allowed accurate distances to be measured.
• B) They emit copious amounts of infrared radiation and are thus visible through interstellar dust,which obscured visible light.
• C) They are concentrated in the galactic center and so defined its direction.
• D) They are important spiral arm tracers and thus defined the shape of the Galaxy.

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Definitions:

Ground

The solid surface of the Earth, where various geological and biological processes occur.

Drumlins

streamlined, elongated hills formed by glacial action, made of till and shaped like inverted spoons.

Sediment

Particles of rock, minerals, or biological materials that have been transported and deposited by wind, water, or ice, often forming layers in bodies of water.

Glacier

A large mass of ice, formed from compacted layers of snow, that moves slowly over land.