Are all hydrogen balmer lines strongest in the same spectrum?
The visible-light Balmer absorption lines of hydrogen are produced by electrons moving from the 1st excited state to a higher orbit. If the star is too cool then most of the hydrogen is in the ground state, so the Balmer lines are not present. On the other hand, if the star is too hot, the electrons are excited to higher levels or the hydrogen is even ionized: again no Balmer lines. The temperature of spectral A type stars is the optimum to populate the first excited state and the Balmer lines are strongest.
