title: On the impact of protoplanetary disk properties on the accretion of super-Earths' atmospheres

authors: Masahiro Ikoma

abstract: A growing number of low-mass exoplanets with short orbital periods have been detected recently. Those exoplanets are often called super-Earths or exo-Neptunes. It has been revealed that a significant fraction of them are low-density ones that are larger in size than water/ice objects. This implies that the short-period super-Earths retain hydrogen-rich atmospheres. Motivated by the fact, we investigate the accretion of hydrogen-rich atmospheres of protoplanets with masses of about 1 to 20 Earth masses that are embedded in warm protoplanetary disks. It is shown that protoplanetary disk properties have significant impacts on the final mass of the hydrogen-rich atmosphere. Our theory is applied to recently detected short-period super-Earths (e.g., ones orbiting Kepler-11) to examine the possibility that the planets are rocky ones with relatively thick H-He atmospheres. Our results demonstrate that low-density super-Earths provide clues to understanding of planetary acc
 retion and disk evolution.