Spectroscopic and photometric study of the Mira stars SU Camelopardalis and RY Cephei

Miras are fascinating stars. A kappa-mechanism in their atmosphere drives pulsations which produce changes in their photometric brightness, apparent spectral type and effective temperature. These pulsations also drive the formation of Balmer emission lines in the spectrum. This behaviour can be observed and investigated with small telescopes. We report on a three-year project combining spectroscopy and photometry to analyse the behaviour of Mira stars SU Cam and RY Cep, and describe how their brightness, colour, spectral type, effective temperature and Balmer emission vary over four pulsation cycles.Comment: 18 pages, 12 figures, 5 tables, accepted for publication in Journal of the AAVSO, references updated for consistency with published versio