The Spiral Arm Structure of the Milky Way Galaxy Has

question 9

Multiple Choice

The spiral arm structure of the Milky Way Galaxy has been measured and evaluated most effectively by observations of

• A) Lyman UV radiation from hot hydrogen gas.
• B) observations of globular clusters in the halo of the Galaxy.
• C) 21-cm radiation from interstellar hydrogen and the positions of young stars.
• D) Balmer emission lines of visible radiation from hydrogen.

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