Large-scale effects of ionizing feedback

TL;DR

This paper reviews recent findings on how ionizing radiation from O-type stars influences gas expulsion, star formation, and cluster unbinding, highlighting that photoionization may be less impactful than previously believed and that observed structures do not always indicate triggered star formation.

Contribution

It provides a critical reassessment of the role of ionizing feedback in star formation and cluster dynamics, emphasizing the natural emergence of structures without necessarily triggering star formation.

Findings

Photoionization is less effective in gas expulsion and star formation triggering than previously thought.

Structures like pillars and bubbles can form naturally without triggering star formation.

The association of stars with ionized structures does not necessarily indicate triggered formation.

Abstract

I discuss recent work on gas expulsion and triggered star formation in, and unbinding of, embedded clusters, by ionizing radiation from O-type stars. Photoionization is not as effective a driver of any of these process as was perhaps once thought. Although structures such as pillars, bubble and champagne flows emerge naturally from the action of ionization on turbulent clouds, the association of stars with such structures does not necessarily imply that they have been triggered.