A tale of two nearby dwarf irregular galaxies WLM and IC 2574 -- as revealed by UVIT

Abstract

We present an ultra-violet study of two nearby dwarf irregular galaxies WLM and IC 2574, using the Far-UV and Near-UV data from the Ultra-Violet Imaging Telescope (UVIT). We used the F148W band Far-UV images and identified 180 and 782 young star-forming clumps in WLM and IC 2574, respectively. The identified clumps have sizes between 7 -30 pc in WLM and 26 -150 pc in IC 2574. We noticed more prominent hierarchical splitting in the structure of star-forming regions at different flux levels in IC 2574 than WLM. We found that the majority of the clumps have elongated shapes in the sky plane with ellipticity ( ) greater than 0.6 in both the galaxies. The major axis of the identified clumps is found to show no specific trend of orientation in IC 2574, whereas in WLM the majority are aligned along south-west to north-east direction. We estimated (F148W−N242W) colour for the clumps identified in WLM and noticed that the younger ones (with (F148W−N242W) < −0.5) are smaller in size (< 10 pc) and are located mostly in the southern half of the galaxy between galactocentric radii 0.4 -0.8 kpc.