Are the Luminosities of RR Lyrae Stars Affected by Second Parameter Effects?

There is a serious discrepancy between the distance to the LMC derived from the Cepheid Period-Luminosity relation and that obtained by using the Galactic calibration for the luminosity of RR Lyrae stars. It is suggested that this problem might be due to the fact that second parameter effects make it inappropriate to apply Galactic calibrations to RR Lyrae variables in the Magellanic Clouds, i.e. Mv(RR) could depend on both [Fe/H] and on one or more second parameters.Comment: 10 pages as uuencoded compressed Postscript. Also available at http://www.dao.nrc.ca/DAO/SCIENCE/science.htm

Measuring the Virial Masses of Disk Galaxies

I present detailed models for the formation of disk galaxies, and investigate which observables are best suited as virial mass estimators. Contrary to naive expectations, the luminosities and circular velocities of disk galaxies are extremely poor indicators of total virial mass. Instead, I show that the product of disk scale length and rotation velocity squared yields a much more robust estimate. Finally, I show how this estimator may be used to put limits on the efficiencies of cooling and feedback during the process of galaxy formation.Comment: 6 pages, 2 fig. To appear in proceedings of "The Mass of Galaxies at Low and High Redshift", eds. R. Bender and A. Renzini (ESO Astrophysics Symposia, Springer-Verlag

Fluctuation theorem for black-body radiation

The fluctuation theorem is verified for black-body radiation, provided the bunching of photons is taken into account appropriately.Comment: 4 pages, 3 figure