Very hot stars have weak hydrogen spectral lines. Why is this?
A) These stars contain very little hydrogen.
B) The hydrogen in the atmospheres of these stars is combined into molecules, and these have different spectra.
C) The electrons in the hydrogen atoms in these stars are all in their lowest energy levels, and they cannot radiate from these levels.
D) The hydrogen atoms in these stars are mostly ionized and hence cannot radiate.

Question

Quizplus · Accepted Answer

The high temperatures in very hot stars ionize hydrogen atoms, stripping away their electrons and leaving them unable to emit the spectral lines characteristic of neutral hydrogen.

Very Hot Stars Have Weak Hydrogen Spectral Lines