SIGNALS of Giant HII Regions: A Spatially Resolved Analysis of NGC 604

Fuente: arXiv
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Autores principales: Garner III, Ray, Kennicutt Jr, Robert C., Drissen, Laurent, Robert, Carmelle, Rousseau-Nepton, Laurie, Morisset, Christophe, Amram, Philippe, Martin, R. Pierre, Jarvis, Emma
Formato: Preprint
Publicado: 2025
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author Garner III, Ray
Kennicutt Jr, Robert C.
Drissen, Laurent
Robert, Carmelle
Rousseau-Nepton, Laurie
Morisset, Christophe
Amram, Philippe
Martin, R. Pierre
Jarvis, Emma
author_facet Garner III, Ray
Kennicutt Jr, Robert C.
Drissen, Laurent
Robert, Carmelle
Rousseau-Nepton, Laurie
Morisset, Christophe
Amram, Philippe
Martin, R. Pierre
Jarvis, Emma
contents Observing giant HII regions at fine spatial scales uncovers detailed structures and reveals variations in ionization, abundance, and dynamical properties of ionized gas and the effect of stellar feedback. Using emission line data of M33 observed with SITELLE as part of the Star-formation, Ionized Gas, and Nebular Abundances Legacy Survey (SIGNALS), we present maps of the principal optical emission line ratios for NGC 604, the most luminous HII region in M33. The excitation maps align well with the H$α$ morphology and are clearly related to the location of the central stellar cluster and secondary stellar groups. The maps of ionization-sensitive line ratios show substantial variations across the face of NGC 604. We demonstrate that these variations are unlikely to be due to chemical inhomogeneities but are primarily caused by changes in ionization, which in turn affect the observed line ratios. We present the H$α$ kinematics of the region and connect it to the excitation structure, showing how the dynamic motions influence the spatial distribution of ionized gas. We note two distinct sources identified in these excitation maps: a known supernova remnant and a previously unknown planetary nebula. Such parsec-scale features contribute only a small percentage to the overall light and would remain undetected without the use of high-resolution spatial data. Throughout the paper, we make comparisons to and raise concerns about single-aperture and long-slit spectroscopic measurements of giant HII regions, highlighting the limitations and potential inaccuracies of such methods.
format Preprint
id arxiv_https___arxiv_org_abs_2510_03144
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SIGNALS of Giant HII Regions: A Spatially Resolved Analysis of NGC 604
Garner III, Ray
Kennicutt Jr, Robert C.
Drissen, Laurent
Robert, Carmelle
Rousseau-Nepton, Laurie
Morisset, Christophe
Amram, Philippe
Martin, R. Pierre
Jarvis, Emma
Astrophysics of Galaxies
Observing giant HII regions at fine spatial scales uncovers detailed structures and reveals variations in ionization, abundance, and dynamical properties of ionized gas and the effect of stellar feedback. Using emission line data of M33 observed with SITELLE as part of the Star-formation, Ionized Gas, and Nebular Abundances Legacy Survey (SIGNALS), we present maps of the principal optical emission line ratios for NGC 604, the most luminous HII region in M33. The excitation maps align well with the H$α$ morphology and are clearly related to the location of the central stellar cluster and secondary stellar groups. The maps of ionization-sensitive line ratios show substantial variations across the face of NGC 604. We demonstrate that these variations are unlikely to be due to chemical inhomogeneities but are primarily caused by changes in ionization, which in turn affect the observed line ratios. We present the H$α$ kinematics of the region and connect it to the excitation structure, showing how the dynamic motions influence the spatial distribution of ionized gas. We note two distinct sources identified in these excitation maps: a known supernova remnant and a previously unknown planetary nebula. Such parsec-scale features contribute only a small percentage to the overall light and would remain undetected without the use of high-resolution spatial data. Throughout the paper, we make comparisons to and raise concerns about single-aperture and long-slit spectroscopic measurements of giant HII regions, highlighting the limitations and potential inaccuracies of such methods.
title SIGNALS of Giant HII Regions: A Spatially Resolved Analysis of NGC 604
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2510.03144