The HII Regions of NGC925 as Observed With SITELLE

Damien Beaulieu ( Université Laval )

The purpose of this work is to explore the HII regions of NGC925 through ionized gas observations and investigate how the diversity of local environment, heightened by the many asymmetries, may impact the star-forming process inside the galaxy. This analysis emerges from the early stages of SIGNALS, an observing survey covering ~35 nearby galaxies with SITELLE, the imaging Fourier transform spectrometer (IFTS) at the Canada-France-Hawaii Telescope. This survey will produce a catalog of more than 50000 HII regions in order to enable a detailed study of the small-scale physics of star-forming regions down to a mean spatial resolution of 20 pc in various local environments. More than 1200 HII regions have been detected in NGC925. Although the galaxy has a conspicuous bar structure, the HII regions show a clear metallicity gradient between the galaxy center and the edge of the disk. This gradient, recent star formation along the bar major axis, the dissonant morphology of the spiral arms and their asymmetric distribution of HII regions suggest that an underlying phenomenon, such as cloud accretion or a minor collision, may have provoked the formation of a bar structure.