Oral Presentation
Scattering-Induced Optical Depth Reduction: Application to the Inner Region of the TW Hya Disk
Presenter: Takahiro Ueda (NAOJ)
Dust continuum observation is one of the best ways to constrain the properties of protoplanetary disks. The recent theoretical studies suggested that the dust scattering potentially reduces the observed intensity, which results in an underestimate in the dust mass. We investigate whether the dust scattering indeed reduces the observed intensity using the ALMA archive data of the TW Hya disk at band 3, 4, 6, 7 and 9.
We find that, in the inner region of the disk, the observed intensities at band 7 and 9 are significantly lower than those estimated from the intensity at band 6 with assuming the spectral index of 2. To investigate the disk properties that can reproduce the ALMA observations, radiative transfer simulations are performed with RADMC-3D. We find that it is hard to explain the observed intensity in the inner region of the disk if the dust scattering is switched off. If we take the dust scattering into account, the observed intensity in the inner region of the disk can be reproduced by the model with the maximum dust size of 300 um with the surface density of 10 g/cm^2 at 10 au, which is 26 times higher than the previous model. The high dust surface density might trigger the planetesimal formation via the streaming instability in the inner region of the TW Hya disk.
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