Why Is 21-Cm Radiation So Important to the Study of Interstellar

question 30

Multiple Choice

Why is 21-cm radiation so important to the study of interstellar matter and the Galaxy?

• A) It helps locate the galactic core in Sagittarius.
• B) Emitted by hydrogen, it passes through interstellar dust and lets us to map the entire Galaxy.
• C) Emitted by carbon monoxide, it passes through interstellar gas and lets us to see places rich in organic molecules around the Galaxy.
• D) It is emitted by most stars, enabling astronomers to map the entire Galaxy.
• E) It is emitted only in hot regions of star formation, so the pattern of the spiral arms of the Galaxy can be mapped.

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