Predictions of Dust Continuum Emission from a Potential Circumplanetary Disk: A Case Study of the Planet Candidate AB Aurigae b

Kavli Affiliate: Ruobing Dong

| First 5 Authors: Yuhito Shibaike, Jun Hashimoto, Ruobing Dong, Christoph Mordasini, Misato Fukagawa

| Summary:

Gas accreting planets embedded in protoplanetary disks are expected to show
dust thermal emission from their circumplanetary disks (CPDs). However, a
recently reported gas accreting planet candidate, AB Aurigae b, has not been
detected in (sub)millimeter continuum observations. We calculate the evolution
of dust in the potential CPD of AB Aurigae b and predict its thermal emission
at 1.3 mm wavelength as a case study, where the obtained features may also be
applied to other gas accreting planets. We find that the expected flux density
from the CPD is lower than the 3-sigma level of the previous continuum
observation by ALMA with broad ranges of parameters, consistent with the
non-detection. However, the expected planet mass and gas accretion rate are
higher if the reduction of the observed near-infrared continuum and H-alpha
line emission due to the extinction by small grains is considered, resulting in
higher flux density of the dust emission from the CPD at (sub)millimeter
wavelength. We find that the corrected predictions of the dust emission are
stronger than the 3-sigma level of the previous observation with the typical
dust-to-gas mass ratio of the inflow to the CPD. This result suggests that the
dust supply to the vicinity of AB Aurigae b is small if the planet candidate is
not the scattered light of the star but is a planet and has a CPD. Future
continuum observations at shorter wavelength are preferable to obtain more
robust clues to the question whether the candidate is a planet or not.

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