Astronomy Colloquium
Sep
9
2025
Sep
9
2025
Description
Determining Stellar Masses in the Galaxy's Richest Environments
The most important factor deciding the fate of a star and its surroundings is its initial mass. The relative number of high- and low-mass stars decides how much light and mass escape from a population of stars. This distribution, the stellar initial mass function, is often assumed to be universally invariant, though we have plenty of reason to believe it varies with environment. I will present results from ALMA observations, including large programs ALMA-IMF and ACES, that measure the mass distribution of pre- and proto-stellar objects at early phases. Denser regions of our Galaxy, like its center, form more stars in clusters than do the outskirts where the Sun resides. Core mass function measurements suggest that more intensely star-forming regions preferentially form high-mass stars. However, the simplest models of core-to-star evolution fail, and I'll show how some have been ruled out using detailed observations of the massive cluster-forming regions W51 and Sgr B2. I'll present a new theoretical framework based on linking radiative transfer models to protostellar accretion history models that we're using to interpret this transition. Finally, I'll show how JWST is changing our view of young and forming massive clusters with a gallery of early results from several imaging programs.
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