Supershells as Molecular Cloud Factories in the Evolving ISM
Naomi McClure-Griffiths, Yasuo Fukui
The compression, cooling and fragmentation of the atomic medium in large-scale colliding flows drives the formation of turbulent, star-forming molecular gas. I will examine the role of supershells as drivers of this process, and more generally as agents of ISM structure formation and evolution. I will report the results of CO(J=1−0) and HI 21cm line observations of two Galactic supershells at parsec resolutions, a key result of which is the measurement of an enhanced level of molecularisation over the volumes of both objects. This result provides quantitative observational evidence of increased molecular cloud production due to the influence of supershells, and paves the way for future expanded studies. However, our observations also highlight the fact that supershells may be destructive to molecular gas on local scales, driving the atomic-molecular transition in the opposite direction in pre-existing clouds disrupted by a shell’s passage.