Abstract
Star and brown dwarf formation theory predicts a mass limit to the turbulent fragmentation of molecular clouds, thought to be 2-10 MJ, providing a natural turnover in the mass function down to planetary masses. Previous studies in the solar neighborhood and nearby star-forming regions identified an increasing mass function from the hydrogen-burning limit down to about 10 MJ, but were not sensitive to lower mass objects. In this talk, I will present results exploring the free-floating planetary mass object population in NGC 2024, a young (< 1 Myr) embedded star-forming region, and the characterization of the initial mass function down to sub-Jupiter masses using JWST/NIRCam. In GTO-1190, we obtained deep imaging of the central core of NGC 2024, covering 0.7 - 5 μm and identified 48 likely cluster members. We find that a broken power-law model of the mass function derived from atmospheric models best represents the data, increasing from 60 MJ to roughly 12 MJ then followed by a decrease down to 0.5 MJ. This is the first evidence for a decrease in the mass function below 10 MJ in a stellar population to date. Our program probes the lowest masses theoretically produced through star formation processes, finding no likely cluster members below about 3 MJ, potentially the fundamental limit of the star and brown dwarf formation process.