SOAR ADAPTIVE OPTICS OBSERVATIONS OF THE GLOBULAR CLUSTER NGC?6496*

摘要

We present high-quality BVRI photometric data in the field of globular cluster NGC?6496 obtained with the SOAR Telescope Adaptive Module (SAM). Our observations were collected as part of the ongoing SAM commissioning. The distance modulus and cluster color excess as found from the red clump are (m – M) V = 15.71 ± 0.02?mag and E(V – I) = 0.28 ± 0.02?mag. An age of 10.5 ± 0.5?Gyr is determined from the difference in magnitude between the red clump and the subgiant branch. These parameters are in excellent agreement with the values derived from isochrone fitting. From the color-magnitude diagram we find a metallicity of [Fe/H] = –0.65?dex and hence support a disk classification for NGC?6496. The complete BVRI data set for NGC?6469 is made available in the electronic edition of the Journal.