Infrared and submillimeter molecular lines from circumplanetary disks

Bochao Hu, Hideko Nomura, Ruobing Dong, Ryan Lau, Takashi Tsukagoshi, Ryohei Kawabe, Tom J. Millar

Planets are formed in protoplanetary disks (PPDs). Recent high spatial resolution observations of the PPDs by infrared large telescopes and by ALMA have revealed point sources, like circumplanetary disks (CPDs), associated with PPDs. One of the examples is discovered in the TW Hya PPD as an au-scale blob at the disk radius of 52 au in dust continuum observations by ALMA (Tsukagoshi et al. 2019), and following the observations, we found a gap-like substructure in the C18O and CS line emission at ~6 au away from the blob, which could be caused by the blob radially migrating towards the central star (Nomura et al. 2021). Preparing for future observations by JWST and ALMA, we have constructed thermo-chemical models of CPDs, making use of radiative transfer calculations and chemical reaction network calculations. Our model calculations suggest that CO, HCN and H2O lines at mid-infrared will be observable by JWST, which will reveal chemical compositions of materials, such as C/O elemental abundance ratio, accreting towards the central planets in CPDs. Meanwhile, ALMA observations of CO lines could reveal kinematics of the CPDs and then the information of the mass of the central planets. These future observations will give us essential physical and chemical properties of planet formation environments.