1209.3772 (Ruobing Dong et al.)

The Structure of Pre-transitional Protoplanetary Disks I: Radiative Transfer Modeling of the Disk+Cavity in the PDS 70 system    [PDF]

Ruobing Dong, Jun Hashimoto, Roman Rafikov, Zhaohuan Zhu, Barbara Whitney, Tomoyuki Kudo, Takayuki Muto, Timothy Brandt, Melissa K. McClure, John Wisniewski, L. Abe, W. Brandner, J. Carson, S. Egner, M. Feldt, M. Goto, C. Grady, O. Guyon, Y. Hayano, M. Hayashi, S. Hayashi, T. Henning, K. W. Hodapp, M. Ishii, M. Iye, M. Janson, R. Kandori, G. R. Knapp, N. Kusakabe, M. Kuzuhara, J. Kwon, T. Matsuo, M. McElwain, S. Miyama, J. -I. Morino, A. Moro-Martin, T. Nishimura, T. -S. Pyo, G. Serabyn, H. Suto, R. Suzuki, M. Takami, N. Takato, H. Terada, C. Thalmann, D. Tomono, E. Turner, M. Watanabe, T. Yamada, H. Takami, T. Usuda, M. Tamura

Through detailed radiative transfer modeling, we present a disk+cavity model to simultaneously explain both the SED and Subaru H-band polarized light imaging for the pre-transitional protoplanetary disk PDS 70. Particularly, we are able to match not only the radial dependence, but also the absolute scale, of the surface brightness of the scattered light. Our disk model has a cavity 65 AU in radius, which is heavily depleted of sub-micron-sized dust grains, and a small residual inner disk which produces a weak but still optically thick NIR excess in the SED. To explain the contrast of the cavity edge in the Subaru image, a factor of ~1000 depletion for the sub-micron-sized dust inside the cavity is required. The total dust mass of the disk may be on the order of 1e-4 M_sun, only weakly constrained due to the lack of long wavelength observations and the uncertainties in the dust model. The scale height of the sub-micron-sized dust is ~6 AU at the cavity edge, and the cavity wall is optically thick in the vertical direction at H-band. If future observations at longer wavelengths reveal the cavity in the ~millimeter-sized grains, then PDS 70 would not be a member of the class of (pre-)transitional disks identified by Dong et al. (2012), whose members only show evidence of the cavity in the millimeter-sized dust but not the sub-micron-sized dust in resolved images. The two classes of (pre-)transitional disks may form through different mechanisms, or they may just be at different evolution stages in the disk clearing process.

View original: http://arxiv.org/abs/1209.3772