A Study of Edge-On Galaxies with the Hubble Space Telescope's Advanced Camera for Surveys. I. Initial Results

Abstract

We present the initial results of a Hubble Space Telescope/ACS snapshot survey of 16 nearby, edge-on, late-type galaxies covering a range in distance from 2 to 19 Mpc. The images of these galaxies show significant resolved stellar populations. We derive F606W and F814W photometry for >1.2 million stars, and present color-magnitude diagrams which show a mixture of young, intermediate, and old stars in each galaxy. In one of the fields we serendipitously detect stars from the Large Magellanic Cloud. We also identify a candidate young dwarf galaxy lying ~2 kpc above the plane of NGC 4631. For the nearest six galaxies, we derive tip of the red giant branch distances and demonstrate that these galaxies fall on the K-band Tully-Fisher relation established in clusters. From the color of the red giant branch, we also find evidence that these galaxies possess a metal-poor thick disk or halo population.

19 pages ApJ format, accepted for publication in the AJ. A higher resolution copy is available at http://www.astro.washington.edu/seth/papers.html