What Is the Tully-Fisher Relation

question 2

Multiple Choice

What is the Tully-Fisher relation?

• A) The more distant the galaxy,the fainter it appears.
• B) The more distant the galaxy,the greater the recessional velocity.
• C) The brighter the Cepheid,the longer the pulsation period.
• D) The brighter the galaxy,the wider the 21-cm radio emission line.

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