Young star clusters in the extended UV disk of M83. Star formation in a low-density, low-metallicity environment

The process of star formation in a low-metallicity environment and whether it differs from star formation in the solar neighborhood is an open topic. Recently, CO clumps were identified within the extended ultraviolet (XUV) disk of M83 despite the low metallicity and distance from the galaxy center, which allowed us to search for any recent star formation in the clumps. We probe whether active star formation occurs within the CO clumps in the XUV disk and assess its implications for star formation in such environments. We analyzed deep Subaru Suprime-Cam Hα, Hyper Suprime-Cam g, r, and i, and Gemini/FLAMINGOS 2 J- and Ks-band imaging to search for evidence of star formation within the ALMA-identified CO clumps. We identified sources within the CO clump contours, and we evaluated the probability that these sources are associated with the CO clumps and are no chance alignments. Based on their magnitudes and adopting single-age stellar population models, we estimated their masses. Four of the clumps have an associated near-infrared counterpart. Based on their magnitude, color, and the general source density in the field, two of these might be chance alignments. One near-infrared counterpart is associated with the most massive clump in the sample, while another is an unresolved cluster near-infrared source with an estimated age of 5 Myr and a mass of 2000 M_⊙. The other, an extended complex, is consistent with an age of 6 Myr and a mass of 700 M_⊙. The near-infrared photometry is sensitive to young clusters with masses down to a few hundred M_⊙ for a fully sampled initial fass function. Star formation is ongoing in a few of the CO clumps, and despite their location in the outskirts of M83, favorable conditions for star formation persist in at least a few clusters. One of the detected sources appears to be interacting with an adjacent molecular clump, which might trigger further star formation.