Silicate clouds and a circumplanetary disk in the YSES-1 exoplanet system

TL;DR

This study presents the first direct detection of silicate clouds in an exoplanet's atmosphere and circumplanetary disk emission in the YSES-1 system, providing insights into early planetary evolution.

Contribution

It reports the first direct observations of silicate clouds in a young exoplanet's atmosphere and circumplanetary disk emission, advancing understanding of planet formation and atmospheric properties.

Findings

Detection of silicate clouds in YSES-1 c's atmosphere.

Identification of silicate emission from YSES-1 b's circumplanetary disk.

Characterization of cloud particle composition and size.

Abstract

Young exoplanets provide a critical link between understanding planet formation and atmospheric evolution. Direct imaging spectroscopy allows us to infer the properties of young, wide orbit, giant planets with high signal-to-noise. This allows us to compare this young population to exoplanets characterized with transmission spectroscopy, which has indirectly revealed the presence of clouds, photochemistry, and a diversity of atmospheric compositions. Direct detections have also been made for brown dwarfs, but direct studies of young giant planets in the mid-infrared were not possible prior to JWST. With two exoplanets around a solar type star, the YSES-1 system is an ideal laboratory for studying this early phase of exoplanet evolution. We report the first direct observations of silicate clouds in the atmosphere of the exoplanet YSES-1 c through its 9-11 micron absorption feature, and the first circumplanetary disk silicate emission around its sibling planet, YSES-1 b. The clouds of YSES-1 c are composed of either amorphous iron-enriched pyroxene or a combination of amorphous MgSiO3 and Mg2SiO4, with particle sizes of less than or equal to 0.1 micron at 1 millibar of pressure. We attribute the emission from the disk around YSES-1 b to be from submicron olivine dust grains, which may have formed through collisions of planet-forming bodies in the disk.