Astrophysics & Planetary Sciences Colloquium

Parker Solar Probe successfully completed its prime mission in 2025, measuring solar wind plasma in-situ as close as 8.8 solar radii (~0.04 AU) from the solar photosphere over a series of close-approach orbits. These close approaches to the Sun enable novel exploration of fundamental stellar processes, such as solar wind acceleration, solar wind heating, interplanetary dust destruction, and radial evolution of solar surface structure. These processes leave distinct signatures in near-Sun particle and field observations that allow us to untangle the physical mechanisms driving them.

The availability of exascale computing resources has enabled numerical modeling of astrophysical fluid dynamics at unprecedented scale, including studies of MHD turbulence on grids with 10,000^{3} cells, or MHD models of black hole accretion in full GR with radiation transport. Results from a diverse range of applications will be presented, including new insights into the structure of radiation-dominated accretion disks, modeling AGN feedback in elliptical galaxies, and turbulence and cosmic ray transport in the interstellar medium.

How big would Mercury need to be to retain an atmosphere? How close could Venus orbit the Sun before its atmosphere erodes away? Are habitable Earth-like atmospheres even possible around the smallest stars? In this talk, I describe how exoplanet observations are starting to provide insight on what environments permit terrestrial planet atmospheres to thrive.

Solar flares and coronal mass ejections (CMEs) are powered by the sudden release of magnetic energy stored in the Sun’s low corona as a result of magnetic reconnection. Understanding these explosive events requires tracking how magnetic fields evolve—not only during, but also before the eruptions. Yet direct measurements of the 3D coronal magnetic field remain a major challenge. In this talk, I will overview what we currently know about the structure of the pre-eruption magnetic field and the physical mechanisms that trigger eruptions.

Abstract: The launch and commissioning of the James Webb Space Telescope is ushering in a new era in our understanding of our cosmic origins. Galaxies are a fundamental building block of the universe, yet how they formed has remained enigmatic owing to our inability to observe them at early cosmic times. In just its first three years of operation, JWST has already upended our understanding of galaxy and black hole growth in the early universe.

Abstract: Field massive stars are more easily identified and studied than those in crowded cluster environments.  While some massive stars may form in relative isolation, most are ejected from clusters via dynamical processes and supernova kicks in binary systems.  Since both mechanisms are driven by binarity in the massive star population, field stars and their kinematics probe the effects of binarity, which can strongly influence stellar evolution by the tr

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Abstract: Lunar volatiles, especially water, hold the key to sustaining long-term human presence on the Moon and beyond.