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

TL;DR

This study combines spectroscopy and photometry over three years to analyze how Mira stars SU Camelopardalis and RY Cep change in brightness, spectral type, temperature, and emission lines across multiple pulsation cycles.

Contribution

It provides a detailed observational analysis of two Mira stars' pulsation behaviors using combined spectroscopic and photometric data over several cycles.

Findings

Brightness and spectral type vary with pulsation phase

Effective temperature correlates with brightness changes

Balmer emission lines appear and vary with pulsations

Abstract

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.