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

TL;DR

This study uses Hubble Space Telescope imaging to analyze stellar populations in 16 nearby edge-on galaxies, revealing diverse star ages, distances, and structural components like thick disks or halos, and identifying a candidate dwarf galaxy.

Contribution

First detailed HST/ACS survey of edge-on galaxies providing extensive stellar photometry, distance measurements, and insights into their structural and stellar population properties.

Findings

Resolved over 1.2 million stars across 16 galaxies.

Derived distances for six galaxies using red giant branch tip.

Identified a candidate dwarf galaxy above NGC 4631.

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.