The Extragalactic Distance Database: Color-Magnitude Diagrams

TL;DR

This paper presents the compilation and analysis of color-magnitude diagrams for approximately 250 nearby galaxies from the Hubble Space Telescope, focusing on measuring the Tip of the Red Giant Branch to estimate galaxy distances.

Contribution

It provides a publicly accessible database of CMDs and stellar photometry for nearby galaxies, facilitating distance measurements using the TRGB method.

Findings

Compilation of CMDs for ~250 galaxies available online

Methodology for constructing CMDs and identifying TRGB

Enables improved distance estimates for local galaxies

Abstract

The CMDs/TRGB (Color-Magnitude Diagrams/Tip of the Red Giant Branch) section of the Extragalactic Distance Database contains a compilation of observations of nearby galaxies from the Hubble Space Telescope. Approximately 250 (and increasing) galaxies in the Local Volume have CMDs and the stellar photometry tables used to produce them available through the web. Various stellar populations that make up a galaxy are visible in the CMDs, but our primary purpose for collecting and analyzing these galaxy images is to measure the TRGB in each. We can estimate the distance to a galaxy by using stars at the TRGB as standard candles. In this paper we describe the process of constructing the CMDs and make the results available to the public.