event
Wednesday 28 Apr 2021: A Balancing Act: Observational determination of the pressures in HII regions across the Galactic Centre and nearby galaxies
Ashley Barnes -
Remote seminar 14:00-15:00
High-mass stars inject a large amount of energy and momentum - stellar feedback - into the interstellar medium (ISM) during their relatively short lifetimes. The feedback from these stars can influence the ISM both locally (<1pc) and across their entire host galaxy (~1kpc), and occurs through a variety of feedback processes; e.g. protostellar outflows, stellar winds, ionizing radiation. The most important of these feedback mechanisms for the overall energy and momentum budget of ISM occurs at the end of the stars lifetime, when they explode as supernovae. However, the efficiency with which SNe couple with their environment strongly depends on their local gas density distribution. Hence, the early pre-SNe feedback processes from high-mass stars play a crucial role in setting this environment into which SNe later explode, and, therefore, in effect limit the efficiency of SNe feedback. In this talk, I will discuss our recent efforts in a quantitative study of pre-SNe feedback mechanisms within both the centre Milky Way, and a large sample of nearby extragalactic systems. In these analyses, we focus on the balance of various internal and external pressures within young HII regions. The study of the Galactic Centre represents the first such study in a high- pressure environment, which has important implications for high-redshift environments. The study of extragalactic systems is the first to attempt such a study on a statistically significant sample of HII regions (>2000). Together, these make key advancements in our understanding of young stellar feedback as a function of environment.
