Poster Abstracts

Name/Affiliation:  Hyein Yu (Ewha Womans University)

Title:  Horizontal-Branch Stars in SDSS: Fiducial Sequences in ugriz and RGB Mass Loss in Open Clusters

We present a set of fiducial sequences of horizontal-branch stars in bright Galactic globular clusters, which have previously been observed in the Sloan Digital Sky Survey (SDSS). We derive fiducial lines on color-magnitude diagrams in multiple color indices (g-r, g-i, g-z, and u-g), and use them to test theoretical predictions from various groups. In addition, we compare various sets of theoretical models to color-magnitude diagrams of M67 and NGC6791 to estimate their red-clump masses, and find that red-clump stars in NGC6791 have lost almost half of their initial masses while ascending the red giant branch. We discuss implications of our finding.