Why Do O- and B-Type Stars Have Weaker Hydrogen Absorption

question 27

Multiple Choice

Why do O- and B-type stars have weaker hydrogen absorption lines than A-type stars?

• A) O- and B-type stars are cooler than A-type stars.
• B) A larger fraction of hydrogen atoms in O- and B-type stars is ionized.
• C) O- and B-type stars have converted much more of their hydrogen into heavier elements.
• D) A-type stars have a higher mass than O- and B-type stars and they have more hydrogen.

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