Desde Mayo 19, 2017 13:15 hasta Mayo 19, 2017 13:45
En Seminar Room
The intrinsic colors of fundamental mode RR Lyrae stars at minimum light have been long known to be a fiducial marker. They were fundamental to the calibration of HI column densities as a reddening measure. We have obtained photometry of nearly 2000 such stars in Galactic bulge, and reconstructed their light curves with DECAM observations in ugriz. From these data we have derived individual line of sight reddening/extinction in an effort to produce not only reddening maps, but also to examine the reddening law, by comparing the color-excesses in different color combinations. These accurate reddening determinations are also used to de-redden the giant branch color-magnitude diagram for the bulge, setting the stage for a population analysis from the Hess diagrams in different regions of the bulge. This is a work still in progress. The DECAM data set, which goes deeper than OGLE, furnishes a rich library of many other kinds of variable stars. I will describe our work, and demonstrate the promise this data-set brings.