2025-05-27 –, Main Conference Room
The wavelengths and sensitivity of JWST have opened a unique window to study the emergence phases of star clusters, as stellar feedback rapidly disrupts the natal molecular clouds—at physical scales previously inaccessible beyond our Galaxy. I will review recent results obtained from combined JWST and HST observations of galaxies spanning the full range of star-forming environments observed in the local universe. Embedded star clusters are now routinely detected in association with 3.3 µm PAH emission and exhibit physical properties indicative of an evolutionary sequence linking them to optically visible star clusters. From the earliest embedded stages, star clusters appear to follow a power-law mass distribution with a slope of –2, consistent with that of optical counterparts.
I will discuss the emerging picture of an evolutionary sequence in which photodissociation regions rapidly fade, giving way to classical H II regions driven by stellar feedback form star clusters. The 3.3 and 7.7 µm polycyclic aromatic hydrocarbon (PAH) bands are found to be sensitive tracers of the earliest phases and typically vanish within ~4 Myr at the locations of emerging star clusters. Evidence suggests that the timescale for emergence varies across galactic environments, with an average of ~6 Myr. This implies that supernovae (SNe) are likely to explode in a medium already shaped by photoionization and stellar winds, potentially exerting a significant impact on the galactic-scale interstellar medium (ISM). Using the FUV spectra of the intervening ISM absorption lines of star clusters in local galaxies, we see: 1. varying coupling efficiency between stellar feedback and surrounding gas, 2. a clear link between cluster mass and the outflow velocities powered by star cluster feedback, 3. and bubbles driven by SNe feedback in line with several studies conducted in the literature.
