Скачать с ютуб S. Choudhury (KASI) - Revealing infall onto the subsonic filaments of B5 core using NH3 observations в хорошем качестве

S. Choudhury (KASI) - Revealing infall onto the subsonic filaments of B5 core using NH3 observations

The study of star formation process requires an understanding of the individual properties and the interplay between different physical structures, such as molecular clouds, cores, and filaments. Due to the vast contrast in their densities, however, it is often difficult to observe these structures in a single tracer. NH3 inversion transitions are useful tracers for this purpose. Although the critical density is relatively low (a few times 103 cm-3), their hyperfine nature allows the individual hyperfines to remain optically thin even at high column densities. Therefore, NH3 can be used to probe the star-forming regions across a wide range of densities and physical scales. Moreover, the presence of multiple hyperfines allows us to obtain very precise constraints on the kinematical information. We used NH3 observations with the Green Bank Telescope and the Very Large Array to study the subsonic dense core Barnard 5, and the compact filaments embedded in it. By fitting multiple components to the observed spectra, we were able to separate the filament components from the core material. In this talk, I will present the physical and kinematical properties of the filaments and the subsonic core. I will then discuss the flow of material that we detect onto the filaments, as well as from the large-scale cloud onto the core. Accretion of fresh material at different scales within dense cores suggests the need for a significant update to our understanding of core evolution and star formation.