CRA Seminar | Dr. Arthur Daniel Adams | University of Virginia| Host: Dr. Gongjie Li

Speaker: Dr. Arthur Daniel Adams

Host: Dr. Gongjie Li

Title: Mapping Sub-stellar Companions in Time and Space

Abstract: Companion brown dwarfs and exoplanets are complex objects whose time and spatial variability are now being mapped with high-fidelity infrared observations from JWST. I will begin by presenting our analysis of JWST NIRSpec/IFU PRISM observations of the 2M1207 system that represent the first spectroscopic time monitoring of a planetary-mass companion simultaneously with its host. By monitoring the variability of the system as a whole, we are sensitive both to the time evolution of atmospheric structure --- including through hot spots and clouds --- as well as external variability such as the accretion of disk material. 2M1207 A's spectra show multiple time-dependent structures across the near-infrared. While we do not see a full rotation within our observations, we do capture non-linear trends in time across much of the spectra, with localized regions showing light curves that hint at the possibility of variability imparted by the circum-stellar disk. The planetary-mass 2M1207 b's spectra generally corroborate the interpretation of recent atmospheric characterizations, where a simple cloud evolution model can capture most of the short-term variability. Turning to spatial variability, I will also provide a first look at the eclipse mapping of brown dwarfs in orbit around white dwarfs. These systems provide a unique opportunity to study the spatially-resolved structures of highly-irradiated atmospheres. Finally, I will highlight ongoing student research in brown dwarfs and exoplanets at UVA, which includes the spectral and orbital characterization of the aforementioned brown-dwarf/white-dwarf binaries as a complement to atmospheric studies, as well as classifying the seasonal evolution of Earth's vegetation as spectral signatures of the response of the majority of Earth's life by mass to the solar energy budget.