Linking stellar populations to HII regions across nearby galaxies: I.
  Constraining pre-supernova feedback from young clusters in NGC1672
  One of the fundamental factors regulating the evolution of galaxies is
stellar feedback. However, we still do not have strong observational
constraints on the relative importance of the different feedback mechanisms
(e.g. radiation, ionised gas pressure, stellar winds) in driving HII region
evolution and molecular cloud disruption. In this letter, we constrain the
relative importance of the various feedback mechanisms from young massive star
populations by resolving HII regions across the disk of the nearby star-forming
galaxy NGC 1672. We combine measurements of ionised gas nebular lines obtained
by PHANGS-MUSE, with high-resolution imaging from the HST in both the
narrow-band H{\alpha} and broad-band filters. We identify a sample of 40
isolated, compact HII regions in the HST H{\alpha} image, for which we measure
the sizes that were previously unresolved in seeing-limited ground-based
observations. Additionally, we identify the ionisation source(s) for each HII
region from catalogues produced as part of the PHANGS-HST survey. We find that
the HII regions investigated are mildly dominated by thermal or wind pressure,
yet their elevation above the radiation pressure is within the expected
uncertainty range. We see that radiation pressure provides a substantially
higher contribution to the total pressure than previously found in the
literature over similar size scales. In general, we find higher pressures
within more compact HII regions, which is driven by the inherent size scaling
relations of each pressure term, albeit with significant scatter introduced by
the variation in the stellar population properties (e.g. luminosity, mass, age,
metallicity). For nearby galaxies, here we provide a promising approach that
could yield the statistics required to map out how the importance of different
stellar feedback mechanisms evolve over the lifetime of an HII region.
