Speaker
Description
A successful theory of star formation should predict the number of objects as a function of their mass produced through star-forming events. Previous studies in star-forming regions and the solar neighborhood have identified a mass function increasing from the hydrogen-burning limit down to about 10 MJ. Theory predicts a limit to the fragmentation process, providing a natural turnover in the mass function down to the opacity limit of turbulent fragmentation, thought to be near 1–10 MJ. In De Furio et al. (2025), we characterized the initial mass function in a young (< 1 Myr) embedded star-forming region, NGC 2024, down to sub-Jupiter masses using photometry from the Near Infrared Camera on the James Webb Space Telescope (JWST). We find a mass function increasing from about 60 MJ to roughly 12 MJ, consistent with previous studies, followed by a decrease down to 0.5 MJ, the first evidence for a decrease in the mass function in a stellar population to date. In GO-5409 (PI: De Furio), we obtained NIRSpec/MSA prism spectroscopy of dozens of candidate sub-stellar members down to ~ 3 MJ in order to confirm membership and better estimate their masses. In this talk, we present the results of our spectroscopic observations and our constraints on the mass function on Jupiter mass scales.
