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M. Rinkoski (Oberlin College), M. W. Castelaz (East Tenn. St. Univ.)
Long-term, phase-comprehensive low resolution spectroscopic observations have been made of M-type Mira variables spanning 4 years. We have determined surface gravities and effective temperatures for R Leo as a function of phase. Spectral observations are compared with synthetic spectra at multiple phases. The synthetic spectra are based on atmospheric models generated by the ATLAS code. Observations are analyzed, and phase dependent plots of effective temperature and log(g) are presented. Phase dependent plots of Teff and log(g) show maximum effective temperature and log(g) at maximum brightness. However, values for Teff and log(g) disagree with the results of non-spectroscopic methods such as stellar interferomtry. Our effective temperatures are cooler and log(g) is smaller. We attribute this discrepancy to LTE approximation of the ATLAS code.
This work was supported by the NSF Research Experience for Undergraduates (REU) Site Program through grant AST 96169939 to Florida Tech and the Southeastern Association for Research in Astronomy (SARA)