EPSCoR Research Fellows: @NASA: Using Simulations to Generate Testable Predictions for the ESPEX mission

When astrophysical objects are born, they accrete mass from the surrounding circumstellar disks. If the central objects are magnetized (including neutron stars, young stars, and young planets), the disk material will be lifted out of the disk and accrete to the central object following the stellar magnetic field lines. This process is called magnetospheric accretion. Magnetospheric accretion onto young stars produces strong ultraviolet (UV) emission at hot spots, which is crucial for measuring the disk accretion rate and understanding disk evolution. UV photons play a significant role in driving disk photo-evaporation and photo-chemistry, which are currently being studied by JWST. The accretion significantly impacts the inner disk, where most exoplanets have been discovered. Given its importance, the Hubble Space Telescope has just completed a new (the largest so far) Director's Discretionary program. Furthermore, a Small Explorers (SMEX) mission program called ESPEX (Early Star and Planet Evolution Explorer) is under investigation at JPL. The PI and the supported graduate student will collaborate with scientists at JPL to generate synthetic observations from PI's simulation data. These observations will be used to make testable predictions for the NASA ESPEX mission and to assist in its design. The proposed study leverages state-of-the-art numerical simulations at UNLV and space mission expertise at JPL to bridge the gap between theory and observations for the ESPEX mission. We will directly analyze the distributions of hot spots on the stellar surface in our simulations, examining both their spatial and temporal evolution to provide a comprehensive overview. We will generate synthetic light curves for the ESPEX mission. Initially, we will calculate the temperature distribution on the stellar surface from our simulations. Then, at a given viewing angle, we will use ray tracing methods to calculate the flux across various wavelength bands at different times. These calculations will assist ESPEX in optimizing its observational strategies. Finally, we will calculate the line profiles from our simulations, which encode both accretion and outflow signatures. The synthetic line profiles will inform our proposals for simultaneous follow-up observations on the ground. We will introduce concepts of observation and NASA mission design to the general public and students at UNLV. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.