Grzegorz Kopacki

Constraints on the Distance Moduli, Helium, and Metal Abundances, and Ages of Globular Clusters from Their RR Lyrae and Non-variable Horizontal Branch Stars. II. Multiple Stellar Populations in 47 Tuc, M3, and M13

We present a new set of horizontal-branch (HB) models computed with the MESA stellar evolution code. The models adopt

Spectroscopic and Photometric Observations of Kepler Asteroseismic Targets

\alpha

Application of the Image Subtraction Method to the OGLE-I Observations

-enhanced \cite{ags09} metals mixtures and include the gravitational settling of He. They are used in our HB population synthesis tool to generate theoretical distributions of HB stars in order to describe the multiple stellar populations in the globular clusters 47Tuc, M3, and M13. The observed HB in 47Tuc is reproduced very well by our simulations for [Fe/H]

Preliminary Results of a Search for Variable Stars in the Globular Cluster M 13

= -0.70

Characteristics of 100+ Kepler Asteroseismic Targets from Ground- Based Observations ?

and [

Wide-field Variability Survey of the Globular Cluster M79 and a New Period -- Luminosity Relation for SX Phe Stars

\alpha

Variable stars in NGC 457

/Fe]

Variable stars in the globular cluster M79

= +0.4

Period-luminosity relationship for SX Phoenicis stars in Galactic globular clusters

if the initial helium mass fraction varies by

Variable Stars in the Open Cluster NGC 7044

\Delta Y_0 \sim 0.03