Jayatee’s Title: Warm chemistry in planet-forming disks

Abstract: The James Webb Space Telescope (JWST) revolutionizes our understanding of planet-forming disks, offering unprecedented insights into their physical and chemical structures. Here, I present the results from JWST MIRI/MRS spectra of disks around very low-mass stars known to have a higher occurrence rate of planets, revealing dust features and, a rich array of large molecules such as C6H6, C4H2, C3H4, C2H6, HC3N, C2H2, CO2 etc. and isotopologues such as 13CCH2 and 13CO2. By leveraging the recently developed extended hydrocarbon chemical network that can form simple aromatics such as C6H6 and using the thermo-chemical disk models, I check if these molecular detections are consistent with our astro-chemical understanding in the high-density inner regions of the disks. As we predominantly observe hydrocarbons in the disk, varying the carbon-to-oxygen (C/O) ratio leads to the formation of these detected species in the surface layers of the disk. There still are unidentified spectral features in the spectra that led me to employ these models to predict additional detectable species. We need the spectrum for these predicted species to confirm or rule out their presence. I then use thermo-chemical disk models to place the slab model results into a larger context and identify the 2D geometry conducive to those conditions. My study paves the way for a deeper understanding of the spectra. It provides new constraints for planet formation in disks around VLMS and highlights the instrumental role of JWST in providing insights into the origins of planetary systems.


Yisheng’s Title: Magnetic Pressure Driven Outflows: Lightly Loaded Jets and Dense Disk Winds in Protostellar Systems

Abstract: Jets and outflows in young stellar objects (YSOs) play a critical role in connecting the inner disk environment with large-scale observables, yet their launching mechanisms remain poorly understood. Observations of both symmetric and asymmetric, including uni-polar, jets raise important questions about the physical processes that govern jet morphology. To investigate these processes, we conduct non-ideal MHD simulations that naturally give rise to three distinct outflow components: (1) a fast, magnetically driven jet along the rotation axis; (2) an MRI-active turbulent disk wind at intermediate cylindrical radii; and (3) a slower, laminar disk wind at larger radii. We find that jets are lightly mass-loaded and launched by toroidal magnetic pressure, bridging features of both classical magneto-centrifugal and magnetic tower models. Crucially, whether MRI-driven turbulent winds fill the polar region and suppress jet launching in one hemisphere, thereby producing asymmetric or uni-polar jets, depends on the interplay between the stellar magnetosphere and the large-scale disk magnetic field. In cases where the disk field dominates, jets are more likely to be one-sided; conversely, a strong, rotating stellar magnetosphere suppresses polar MRI activity and facilitates the launching of symmetric, bipolar jets. This sensitivity to magnetic field topology provides an observational handle for probing the relative roles of stellar and disk magnetism.