Hydrogen lines are weak in the spectra of hot O-type stars because ____.
A) most of the hydrogen has been converted to helium
B) a good spectrum of these stars is difficult to obtain
C) these stars have no atmosphere
D) gravitational pressure pushes all the hydrogen lines out of the visible spectrum
E) most of the hydrogen is ionized to high energy levels

Question

Quizplus · Accepted Answer

In hot O-type stars, the high temperatures cause most of the hydrogen to be ionized, meaning electrons are stripped from the hydrogen atoms. This ionization process results in weak hydrogen lines in their spectra, as the typical transitions associated with hydrogen's spectral lines are less likely to occur.

Hydrogen Lines Are Weak in the Spectra of Hot O-Type