Annie Maloney Wins 2025 Stoddard Prize for Best Senior Thesis
Annie Maloney, a recent University of Rochester graduate in the class of 2025 with a BS in physics and astronomy, has won the 2025 Stoddard Prize for Best Senior Thesis at the Department of Physics and Astronomy (PAS) for their undergraduate research supported by the LLE Undergraduate Program. Annie has been co-advised by Brennan Arnold (Horton Fellow, PAS), Eric Blackman (PAS, LLE), and Suxing Hu (LLE, PAS). The title of their thesis is “Investigating Radiative Levitation in White Dwarf Stars Using Large-Scale Molecular Dynamics Simulations.”
Annie’s thesis consists of computational work and analysis motivated by observations of heavy metals in the atmospheres of white dwarfs—the compact remnants of low-mass stars. These heavy elements may have been supplied by tidally shredded planets but would be expected to have quickly disappeared into the white dwarf interiors if subjected only to the force of gravity. Their observed persistence suggests that some outward force is competing with gravity. One possibility is that radiation from the white dwarf interior is absorbed by the heavy atoms, levitating them. Such radiative levitation has been previously proposed but not quantified for the high-pressure conditions of white dwarfs. Annie’s thesis uses a state-of-the-art molecular dynamics code (LAMMPS) to study the process in a high-pressure hydrogen and silicon plasma that quantifies, for the first time, how effectively the radiation force accelerates and lifts the silicon, and identifies a competing, substantial drag force associated with collisions with background hydrogen. The work represents the first step needed to quantify the efficacy of radiative levitation in stellar models.
Annie is now being nominated for the APS LeRoy Apker Award, and this coming fall, they will attend Washington University in St. Louis to pursue their PhD in the Department of Earth, Environmental, and Planetary Sciences. Congratulations, Annie!
