April 1
Clouds, Ions, and Planetesimals: The Story of Refractory Elements in Exoplanets and Brown Dwarfs
Speaker: Dr. Joshua Lothringer, STScI
Abstract: Unlike in the Solar System’s giant planets, refractory elements like Fe, Mg, and Si participate in a variety of interesting atmospheric phenomena in irradiated exoplanets and self-luminous brown dwarfs. I will describe our current understanding of the behavior of these refractory elements through new HST and JWST observations of hot Jupiters and cloudy brown dwarfs. First, high-resolution NUV transit spectra of ultra-hot Jupiters are revealing a “cosmic shoreline” of Mg II escape, providing insight into planetary mass-loss while testing an interpretative framework used for rocky planets. Second, we measure the refractory-to-volatile ratio of ultra-hot Jupiters with UV-to-IR transmission spectra, inferring the rock-to-ice ratio to constrain planet formation and migration scenarios. Lastly, we explore what happens when these refractory elements condense by presenting new JWST spectra of two cloudy brown dwarfs, measuring cloud particle composition, crystallinity, particle size, and vertical distribution to unprecedented precision. Combined, these results show the wealth of information revealed by studying the behavior of heavy elements with the combined power of HST and JWST.
Host: Dr. Megan Weiner Mansfield