Highly excited hydrogen lines in stellar spectra. II

Abstract

In the first part of the paper the shifts of the last visible balmer lines as a function of the gas density were predicted theoretically. Here spectroscopic research for these shifts is reported: 10A/mm⁻¹ spectra of six stars were examined and published material of other authors was also used.

The shifts are of tenth Angström order of magnitude and they are used to measure the gas density in a well defined region of the stellar atmosphere. It is shown that usually there is no real coalescence of Balmer lines. The lack of Balmer lines with high main quantum number is explained adequately in most cases without Stark and Doppler effect. Evidence is given against using the Inglis-Teller formula because its physical foundation is inadequate. It gives false values in general.

Stars with peculiar spectra—helium and carbon Wolf-Rayet stars—are briefly mentioned as well because the last visible Balmer-like line of Hei orCiv gives a density value in their atmospheres which is a useful first guess in understanding their spectra better.