PHYS/ASTR Colloquium: "Abundances & Atmospheres: Connecting the Dots in Benchmark Brown Dwarfs" - Dr. Caprice Phillips (NASA Sagan Fellow at UC Santa Cruz)

San Francisco State University
Physics & Astronomy Colloquium Series
Monday, November 17, 2025
SEIC 210, 3:30 PM

Dr. Caprice Phillips (NASA Sagan Fellow at UC Santa Cruz)
Title: Abundances & Atmospheres: Connecting the Dots in Benchmark Brown Dwarfs

Abstract: The atmospheric compositions of substellar objects provide insight into their formation pathways and the physical processes governing their evolution. Stellar elemental abundances likewise inform the initial conditions of protoplanetary disks. In this talk, I will present spectral retrieval and stellar abundance analyses of benchmark brown dwarfs and their solar-type host stars. For planetary-mass analogs and intermediate-mass brown dwarfs, I will discuss the use of retrievals and forward modeling to determine atmospheric compositions and formation diagnostics, including carbon-to-oxygen ratios, across the cloudy L-dwarf regime with near-infrared data. I will summarize key results and lessons from these analyses. I will also present ongoing PEPSI/LBT abundance measurements for host stars, aimed at constraining formation histories, ages, cloud-formation reservoirs (e.g., Y/Mg, Mg/Si, Ca/Al, S/N, C/O), and spectroscopic parameters for this benchmark sample.

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