Sebastian Zieba and Brianna Zawadzki

From the calendar

Rocky planets orbiting M-dwarf stars are among the most common planets known in the galaxy. While many of these worlds have similar densities to the Solar System terrestrial planets, they may have vastly different atmospheres and geology due to their short-period orbits. Here, I will present a recent result from JWST to characterize the surface of a rocky exoplanet: Previous Spitzer observations of the hot planet LHS3844b indicate that it is most likely a bare rock, inviting detailed study of the surface. We used MIRI/LRS (5 - 12 microns) on JWST to observe three eclipses of the planet, leading to a confident detection of thermal emission coming from the planet. Our emission spectrum tightly constrains the surface composition, between possibilities like basalt, ultramafic rock, and granite. Furthermore, we recently took a phase curve of the planet with NIRSpec G395H, which additionally constrains the surface composition between 2.7 and 5.2 microns. These JWST observations provide the first empirical constraints on the geologic history of a rocky exoplanet orbiting an M-dwarf.

Debris disks are tenuous reservoirs of dust and gas around main sequence stars which probe the critical time domain between planet formation (in protoplanetary disks at ≲10 Myr) and mature planetary systems (mostly detected at ages of Gyrs). Millimeter wavelength observations are particularly important for dust characterization; larger grains probed by these observations trace the dynamics of the system and are not strongly affected by radiation pressure and stellar winds. Dozens of debris disks have been imaged with ALMA at low resolution, but only a handful of sources have previously been observed with sensitivities and resolutions sufficient to detect substructure like rings and gaps. This is especially true for characterizing the vertical structure of debris disks, which requires high-resolution observations of highly inclined disks. Well-resolved vertical structure measurements at millimeter wavelengths provide direct insight into the degree of dynamical excitation within the disk, enabling us to infer the presence of a wide range of planets (down to Earth masses) and determine the prevalence of Neptune-like migration histories. The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) is observing 18 debris disks at high resolution, including 11 highly inclined (i > 68°) sources, which we add to two archival sources for a uniform sample of 13 disks with well-resolved vertical structure at millimeter wavelengths. We will present the results of the ARKS vertical structure analysis using this sample of high-resolution observations to measure debris disk scale heights, constrain their total masses, and confirm or rule out the presence of planets.