James Webb Space Telescope Feed Post

Harvard ADS: Identification of a turnover in the initial mass function of a young stellar cluster down to 0.5 M_{J}

Paper abstract: 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 identify a mass function increasing from the hydrogen-burning limit down to about 10 M_{J}. 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 2-10 M_{J}. Programs to date have not been sensitive enough to probe the hypothesized opacity limit of fragmentation. Here we present the first identification of a turnover in the initial mass function below 12 M_{J} within NGC 2024, a young star-forming region. With JWST/NIRCam deep exposures across 0.7-5 {\mu}m, we identified several free floating objects down to ~ 3 M_{J} with sensitivity to 0.5 M_{J}. We present evidence for a double power law model increasing from about 60 M_{J} to roughly 12 M_{J}, consistent with previous studies, followed by a decrease down to 0.5 M_{J}. Our results support the predictions of star and brown dwarf formation theory, identifying the theoretical turnover in the mass function and suggest the fundamental limit of turbulent fragmentation near 3 M_{J}.