Atomic hydrogen, star formation and feedback in the lowest mass Blue Compact Dwarf galaxies

TL;DR

This study investigates the properties of the lowest mass Blue Compact Dwarf galaxies in the M81 group, focusing on their HI content, star formation activity, and feedback effects, revealing faint emissions, spatial offsets, and limited feedback evidence.

Contribution

It provides new observations of extremely low-mass BCDs, highlighting their HI masses, star formation characteristics, and the limited impact of feedback in such small galaxies.

Findings

HI detected in three low-mass BCDs with ~10^6 M_sun

Offsets observed between FUV and H-alpha emission regions

Tentative evidence of outflowing HI gas in one galaxy

Abstract

We present the results from a search for HI emission from a sample of newly discovered dwarf galaxies in the M81 group. HI is detected in three galaxies, all of which are classified as BCDs. The HI masses of these galaxies are ~ 10^6 M_sun, making these some of the lowest mass BCDs known. For these three galaxies FUV images (from GALEX) and H-alpha images (from the Russian 6m BTA telescope) are available.The H-alpha emission is very faint, and, in principle could be produced by a single O star. Further, in all cases we find offsets between the peak of the FUV emission and that of the H-alpha emission. Offsets between the most recent sites of star formation (i.e. those traced by H-alpha) and the older sites (i.e. those traced by FUV) would be natural if the star formation is stochastic. In spite of the expectation that the effects of mechanical feedback from star formation would be most directly seen in the smallest galaxies with low gravitational potentials, we only see tentative evidence of outflowing HI gas associated with the star forming region in one of the galaxies.