Host: Xianyu Tan
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Abstract:
Atmospheric clouds strongly shape the observed spectra of brown dwarfs and gas giant exoplanets, making them fundamental to understanding substellar atmospheres. In particular, silicate clouds are ubiquitous in warm brown dwarfs and are now beginning to be detected in a growing number of hot exoplanet atmospheres through JWST observations. In this talk, I present new JWST and archival Spitzer mid-infrared spectra of cloudy brown dwarfs spanning a wide range of temperatures, metallicities, ages, and viewing geometries. Using these data, I investigate the formation, composition, evolution, and spatial distribution of silicate clouds and their dependence on fundamental parameters. Key results include: (1) the onset and sedimentation of silicate clouds between ~2000–1300 K, (2) evidence of complex grain chemistry such as iron-rich silicates, (3) a concentration of silicate clouds at low latitudes, leading to redder colors in equator-on objects, (4) an age dependence in the direct spectral signature produced by silicate clouds, (5) suppressed cloud formation at low metallicity, and (6) a strong anticorrelation between spectral features from gas molecules and grain species. These results provide new insight into the role of clouds in shaping ultracool atmospheric spectra.
Biography:
Genaro Suárez is a postdoctoral researcher in the Department of Astrophysics at the American Museum of Natural History (AMNH) and a member of the Brown Dwarfs in New York City (BDNYC) research group. His research focuses on the atmospheres of giant exoplanets and brown dwarfs, using both ground- and space-based telescopes to characterize their composition and physical properties. He earned his PhD in Astronomy from the National Autonomous University of Mexico (UNAM) in 2019, followed by a postdoctoral position at the University of Western Ontario in Canada. He also studies the formation of brown dwarfs and stars through the initial mass function and is very passionate about open-source software development and science communication.
