Heating from accreting protoplanets affects CO observations
Although recent observations of protoplanetary disks have unveiled plethora of sub-structures that can be attributed to unseen protoplanets, direct detections of signals from circumplanetary regions are incredibly rare. In Chrenko et al. (2025), we investigated whether accreting protoplanets can induce observable variations in the CO line emission by heating up their circumplanetary environment, sublimating CO ice, and increasing the respective gas-phase abundance. For the mechanism to work, we assumed large orbital distances outside the CO snowline where CO is frozen out at the disk midplane. As shown in the figure on the left, a luminous Jupiter-mass protoplanet can elevate the disk temperature and sublimate CO in a bubble comparable in size to the Hill sphere. At a suitable viewing geometry, the bubble becomes visible because CO molecules are absent from most of the midplane, except for the circumplanetary region. Nevertheless, detections of CO bubbles are challenging with the current ALMA capabilites, even when state-of-the-art kinematics tools are applied.
