CFHT UM2025 - Presentation Details
Abstract Details
Title: SIGNALS: NGC 4395 H II Regions Properties
Presenter: Mykola Posternak
Abstract:
As part of SIGNALS, NGC 4395 was observed with SITELLE. Using a detection code developed at Université Laval, well adapted for SITELLE data, 1156 emission-line regions were identified across the entire disk of this nearby (4.3 Mpc), nearly face-on, low-mass galaxy. Although relatively isolated, NGC 4395 exhibits asymmetries characterized by very bright H II region complexes on its southern arm. BPT diagrams and kinematic analysis confirm that most of these regions are H II regions. The SIGNALS H II region catalogue for NGC 4395 far surpasses previous ones. A comparison of Hα surface brightness and equivalent width, velocity dispersion, and position in BPT diagrams between H II regions and the diffuse ionized gas suggests that the latter is mainly produced by leaking photons from H II regions. Metallicity measurements reveal a shallow radial gradient, with a mean metallicity of 12 log(O/H) = 8.51 ± 0.02. The brightest H II regions in the southern arm do not exhibit any particularly unusual properties, aside from their overlap with a bright 24 μm dust cloud, suggesting a link to younger and/or more massive stellar clusters. Overall, with a star formation rate of 0.13 M☉/yr, NGC 4395’s activity appears to result from a galactic evolution driven by slow internal processes.