Spatial segregation impact on star formation in nearby dwarf spheroidal galaxies

TL;DR

This study uses HST/ACS data to analyze the star formation histories of nearby dwarf spheroidal galaxies, revealing complex histories influenced by their spatial environment and segregation.

Contribution

It provides a homogeneous analysis of star formation histories across different dwarf spheroidals, highlighting the impact of spatial segregation on their evolution.

Findings

All galaxies show complex star formation histories with ancient and intermediate-age stars.

Spatial environment correlates with differences in star formation parameters.

Segregation influences the evolutionary pathways of dwarf spheroidal galaxies.

Abstract

Using our HST/ACS observations of the recently found isolated dwarf spheroidal galaxies, we homogeneously measured their star formation histories. We determined star formation rate as a function of time, as well as age and metallicity of the stellar populations. All objects demonstrate complex star formation history, with a significant portion of stars formed 10-13 Gyr ago. Nevertheless, stars of middle ages (1-8 Gyr) are presented. In order to understand how the star formation parameters influence the evolution of dSphs, we also studied a sample of nearest dSphs in different environment: isolated (d < 2 Mpc); beyond the Local Group virial radius (but within the Local Group zero velocity sphere); and the satellites of M 31 located within the virial zone (300 kpc). Using archival HST/ACS observations, we measured their star formation histories. A comparative analysis of the parameters obtained allow us to distinguish a possible effect of the spatial segregation on the dSphs evolution scenario.