Numerical Color-Magnitude Diagram Analysis of SDSS Data and Application to the New Milky Way satellites

TL;DR

This paper evaluates and applies the MATCH software to Sloan Digital Sky Survey data for analyzing stellar populations and distances in globular clusters and new Milky Way satellites, revealing their properties and star formation histories.

Contribution

It demonstrates the effectiveness of CMD-fitting techniques on SDSS data and introduces new methods for analyzing extended and sparse stellar populations in wide-area surveys.

Findings

MATCH accurately recovers known properties of globular clusters.

Most satellites have single stellar populations, but some show complex star formation histories.

The methods enable detection of stellar overdensities in large survey data.

Abstract

We have tested the application to Sloan Digital Sky Survey data of the software package MATCH, which fits color-magnitude diagrams (CMDs) to estimate stellar population parameters and distances. These tests on a set of six globular clusters show that these techniques recover their known properties. New ways of using the CMD-fitting software enable us to deal with an extended distribution of stars along the line-of-sight, to constrain the overall properties of sparsely populated objects, and to detect the presence of stellar overdensities in wide-area surveys. We then also apply MATCH to CMDs for twelve recently discovered Milky Way satellites to derive in a uniform fashion their distances, ages and metallicities. While the majority of them appear consistent with a single stellar population, CVn I, UMa II, and Leo T exhibit (from SDSS data alone) a more complex history with multiple epochs of star formation.