| Star forming dwarf galaxies are thought to be the first structures that form in the hierarchical structure formation scenario, and are extreme systems with very low pressure, dust, metallicity, etc. We study the correlation between atomic gas as traced by HI, and star formation as traced by far-ultraviolet emission (FUV) and Hydrogen recombination line (H alpha), in the faintest star forming dwarf galaxies. We also investigate the dichotomy of star formation rates deduced from these two different tracers, for these galaxies.
The figure shows a multiwavelength image of the dwarf irregular galaxy DDO 125. Inside the strangely shaped HI cloud (green) lies a star forming disc about 3 kpc in size, as revealed by FUV emission detected by GALEX (blue). Massive stars are forming in the regions with dense HI, traced by the H-alpha image from the 6m BTA telescope (pink).