[437] Sitz. d. Preuss. Ac., 47, 1198, 1914.
CHAPTER XII
SPECIAL PROBLEMS IN STELLAR ATMOSPHERES
THE greater part of the present work has dealt with the discussion and interpretation of the normal spectral sequence,
to
, and the main features of the series have been satisfactorily attributed to thermal ionization at high temperatures. Such a discussion must naturally be the first step in the analysis of the stellar atmosphere. When the more general results of observation have been reduced, in some measure, to an orderly system, it becomes possible to consider special problems involving stars or groups of stars, which lie outside the system, or which, though included in the system, display definite abnormalities.
The special problems of stellar spectroscopy are very numerous. We may mention the novae, the Class
