Supergiant Properties

The intent of this work is to provide an improved, direct effective temperature calibration for supergiants. By using interferometrically determined angular diameters for 42 Luminosity Class (LC) I and 32 LC II stars from the Palomar Testbed Interferometer, as well as improved photometry, we will improve upon the effective temperatures determined in van Belle et al. (2009). Recent improvements in available archival photometry provide a much richer and more accurate data set than used in the original calculations, augmented by new observational data. For consistency, we utilize the same spectral energy distribution (SED) code and spectral templates to create a more accurate but directly comparable effective temperature calibration. The effective temperature measurement is improved through improved bolometric flux and reddening values that result from the improved photometry constraining the SED fits. Most of our attention is focused on better determination of the reddening values to confirm or rule out any possible bias in the original work. As a secondary comparison, we are exploring any possible relative bias between our interferometric work and Levesque et al.'s (2009) spectroscopic analysis of supergiant effective temperatures, through comparison of the reddening and bolometric flux values.