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Title: THE MISSING CAVITIES IN THE SEEDS POLARIZED SCATTERED LIGHT IMAGES OF TRANSITIONAL PROTOPLANETARY DISKS: A GENERIC DISK MODEL

Abstract

Transitional circumstellar disks around young stellar objects have a distinctive infrared deficit around 10 {mu}m in their spectral energy distributions, recently measured by the Spitzer Infrared Spectrograph (IRS), suggesting dust depletion in the inner regions. These disks have been confirmed to have giant central cavities by imaging of the submillimeter continuum emission using the Submillimeter Array (SMA). However, the polarized near-infrared scattered light images for most objects in a systematic IRS/SMA cross sample, obtained by HiCIAO on the Subaru telescope, show no evidence for the cavity, in clear contrast with SMA and Spitzer observations. Radiative transfer modeling indicates that many of these scattered light images are consistent with a smooth spatial distribution for {mu}m-sized grains, with little discontinuity in the surface density of the {mu}m-sized grains at the cavity edge. Here we present a generic disk model that can simultaneously account for the general features in IRS, SMA, and Subaru observations. Particularly, the scattered light images for this model are computed, which agree with the general trend seen in Subaru data. Decoupling between the spatial distributions of the {mu}m-sized dust and mm-sized dust inside the cavity is suggested by the model, which, if confirmed, necessitates a mechanism, such as dustmore » filtration, for differentiating the small and big dust in the cavity clearing process. Our model also suggests an inwardly increasing gas-to-dust ratio in the inner disk, and different spatial distributions for the small dust inside and outside the cavity, echoing the predictions in grain coagulation and growth models.« less

Authors:
; ; ; ;  [1];  [2];  [3];  [4]; ;  [5];  [6];  [7]; ;  [8];  [9];  [10];  [11];  [12];  [13];  [14] more »; « less
  1. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
  2. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48105 (United States)
  3. Astronomy Department, University of Wisconsin-Madison, 475 N. Charter Street, Madison, WI 53706 (United States)
  4. Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551 (Japan)
  5. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
  6. ExoPlanets and Stellar Astrophysics Laboratory, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  7. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
  8. Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501 (Japan)
  9. Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands)
  10. Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States)
  11. Graduate University for Advanced Studies (SOKENDAI), Shonan International Village, Hayama-cho, Miura-gun, Kanagawa 240-0193 (Japan)
  12. Laboratoire Lagrange, UMR7293, Universite de Nice-Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, 06300 Nice (France)
  13. Max Planck Institute for Astronomy, Heidelberg (Germany)
  14. Department of Physics and Astronomy, College of Charleston, 58 Coming Street, Charleston, SC 29424 (United States)
Publication Date:
OSTI Identifier:
22034465
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 750; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; COMPUTERIZED SIMULATION; COSMIC DUST; DECOUPLING; DENSITY; ENERGY SPECTRA; IMAGES; MAIN SEQUENCE STARS; NEAR INFRARED RADIATION; PHOTON EMISSION; PROTOPLANETS; RADIANT HEAT TRANSFER; SPATIAL DISTRIBUTION; VISIBLE RADIATION

Citation Formats

Dong, R., Rafikov, R., Zhu, Z., Brandt, T., Janson, M., Hartmann, L., Whitney, B., Muto, T., Hashimoto, J., Kuzuhara, M., Grady, C., Follette, K., Tanii, R., Itoh, Y., Thalmann, C., Wisniewski, J., Mayama, S., Abe, L., Brandner, W., Carson, J., E-mail: rdong@astro.princeton.edu, and and others. THE MISSING CAVITIES IN THE SEEDS POLARIZED SCATTERED LIGHT IMAGES OF TRANSITIONAL PROTOPLANETARY DISKS: A GENERIC DISK MODEL. United States: N. p., 2012. Web. doi:10.1088/0004-637X/750/2/161.
Dong, R., Rafikov, R., Zhu, Z., Brandt, T., Janson, M., Hartmann, L., Whitney, B., Muto, T., Hashimoto, J., Kuzuhara, M., Grady, C., Follette, K., Tanii, R., Itoh, Y., Thalmann, C., Wisniewski, J., Mayama, S., Abe, L., Brandner, W., Carson, J., E-mail: rdong@astro.princeton.edu, & and others. THE MISSING CAVITIES IN THE SEEDS POLARIZED SCATTERED LIGHT IMAGES OF TRANSITIONAL PROTOPLANETARY DISKS: A GENERIC DISK MODEL. United States. doi:10.1088/0004-637X/750/2/161.
Dong, R., Rafikov, R., Zhu, Z., Brandt, T., Janson, M., Hartmann, L., Whitney, B., Muto, T., Hashimoto, J., Kuzuhara, M., Grady, C., Follette, K., Tanii, R., Itoh, Y., Thalmann, C., Wisniewski, J., Mayama, S., Abe, L., Brandner, W., Carson, J., E-mail: rdong@astro.princeton.edu, and and others. Thu . "THE MISSING CAVITIES IN THE SEEDS POLARIZED SCATTERED LIGHT IMAGES OF TRANSITIONAL PROTOPLANETARY DISKS: A GENERIC DISK MODEL". United States. doi:10.1088/0004-637X/750/2/161.
@article{osti_22034465,
title = {THE MISSING CAVITIES IN THE SEEDS POLARIZED SCATTERED LIGHT IMAGES OF TRANSITIONAL PROTOPLANETARY DISKS: A GENERIC DISK MODEL},
author = {Dong, R. and Rafikov, R. and Zhu, Z. and Brandt, T. and Janson, M. and Hartmann, L. and Whitney, B. and Muto, T. and Hashimoto, J. and Kuzuhara, M. and Grady, C. and Follette, K. and Tanii, R. and Itoh, Y. and Thalmann, C. and Wisniewski, J. and Mayama, S. and Abe, L. and Brandner, W. and Carson, J., E-mail: rdong@astro.princeton.edu and and others},
abstractNote = {Transitional circumstellar disks around young stellar objects have a distinctive infrared deficit around 10 {mu}m in their spectral energy distributions, recently measured by the Spitzer Infrared Spectrograph (IRS), suggesting dust depletion in the inner regions. These disks have been confirmed to have giant central cavities by imaging of the submillimeter continuum emission using the Submillimeter Array (SMA). However, the polarized near-infrared scattered light images for most objects in a systematic IRS/SMA cross sample, obtained by HiCIAO on the Subaru telescope, show no evidence for the cavity, in clear contrast with SMA and Spitzer observations. Radiative transfer modeling indicates that many of these scattered light images are consistent with a smooth spatial distribution for {mu}m-sized grains, with little discontinuity in the surface density of the {mu}m-sized grains at the cavity edge. Here we present a generic disk model that can simultaneously account for the general features in IRS, SMA, and Subaru observations. Particularly, the scattered light images for this model are computed, which agree with the general trend seen in Subaru data. Decoupling between the spatial distributions of the {mu}m-sized dust and mm-sized dust inside the cavity is suggested by the model, which, if confirmed, necessitates a mechanism, such as dust filtration, for differentiating the small and big dust in the cavity clearing process. Our model also suggests an inwardly increasing gas-to-dust ratio in the inner disk, and different spatial distributions for the small dust inside and outside the cavity, echoing the predictions in grain coagulation and growth models.},
doi = {10.1088/0004-637X/750/2/161},
journal = {Astrophysical Journal},
number = 2,
volume = 750,
place = {United States},
year = {Thu May 10 00:00:00 EDT 2012},
month = {Thu May 10 00:00:00 EDT 2012}
}
  • We explore whether protoplanetary disks with self-shadowing from puffed-up inner rims exhibit observable features in scattered light images. We use both self-consistent hydrostatic equilibrium calculations and parameterized models to produce the vertically puffed-up inner rims. We find that, in general, the transition between the shadowed and flared regions occurs in a smooth manner over a broad radius range, and no sudden jump exists at the outer edge of the shadow in either the disk temperature or density structures. As a result, a puffed-up rim cannot create sharp ring/arc/spiral-arm-like features in the outer disk as have been detected in recent directmore » near-infrared imaging of disks. On the other hand, if the puffed-up rim has a sharp edge in the vertical direction, the shadowing effect can produce a distinct three-stage broken power law in the radial intensity profile of the scattered light, with two steep surface brightness radial profiles in the inner and outer disk joined by a shallow transition region around the shadow edge. These types of scattered light profiles may have already been observed, such as in the recent Subaru direct imaging of the TW Hydrae system.« less
  • We present H- and K {sub s}-band polarized differential images of the Herbig Ae/Be star HD142527, revealing its optically thick outer disk and the nearly empty gap. The very small inner working angle (∼0.''1) and high-resolution achievable with an 8 m class telescope, together with a careful polarimetric calibration strategy, allow us to achieve images that surpass the quality of previous scattered-light images. Previously known substructures are resolved more clearly and new structures are seen. Specifically, we are able to resolve (1) half a dozen spiral structures in the disk, including previously known outer-disk spirals as well as new spiralmore » arms and arcs close to the inner rim of the disk, (2) peculiar holes in the polarized surface brightness at position angles (P.A.'s) of ∼0° and ∼160°, (3) the inner rim on the eastern side of the disk, and (4) the gap between the outer and inner disk, ranging from the inner working angle of 0.''1 out to between 0.''7 and 1.''0, which is nearly devoid of dust. We then use a Markov Chain Monte Carlo algorithm to determine several structural parameters of the disk, using very simple assumptions, including its inclination, eccentricity, and the scale height of the inner rim. We compare our results with previous work on this object and try to produce a consistent picture of the system and its transition disk.« less
  • Through detailed radiative transfer modeling, we present a disk+cavity model to simultaneously explain both the spectral energy distribution (SED) and Subaru H-band polarized light imaging for the pre-transitional protoplanetary disk PDS 70. In particular, 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 that produces a weak but still optically thick near-IR excess in the SED. To explain the contrast of themore » cavity's edge in the Subaru image, a factor of {approx}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 10{sup -4} M {sub 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 {approx}6 AU at the cavity edge, and the cavity wall is optically thick in the vertical direction at H-band. PDS 70 is not a member of the class of (pre-)transitional disks identified by Dong et al., whose members only show evidence of the cavity in the millimeter-size 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 simply be at different evolution stages in the disk-clearing process.« less
  • Circumstellar disks are thought to experience a rapid 'transition' phase in their evolution that can have a considerable impact on the formation and early development of planetary systems. We present new and archival high angular resolution (0.''3 {approx} 40-75 AU) Submillimeter Array (SMA) observations of the 880 {mu}m (340 GHz) dust continuum emission from 12 such transition disks in nearby star-forming regions. In each case, we directly resolve a dust-depleted disk cavity around the central star. Using two-dimensional Monte Carlo radiative transfer calculations, we interpret these dust disk structures in a homogeneous, parametric model framework by reproducing their SMA continuummore » visibilities and spectral energy distributions. The cavities in these disks are large (R{sub cav} = 15-73 AU) and substantially depleted of small ({approx}{mu}m-sized) dust grains, although their mass contents are still uncertain. The structures of the remnant material at larger radii are comparable to normal disks. We demonstrate that these large cavities are relatively common among the millimeter-bright disk population, comprising at least 1 in 5 (20%) of the disks in the bright half (and {>=}26% of the upper quartile) of the millimeter luminosity (disk mass) distribution. Utilizing these results, we assess some of the physical mechanisms proposed to account for transition disk structures. As has been shown before, photoevaporation models do not produce the large cavity sizes, accretion rates, and disk masses representative of this sample. A sufficient decrease of the dust optical depths in these cavities by particle growth would be difficult to achieve: substantial growth (to meter sizes or beyond) must occur in large (tens of AU) regions of low turbulence without also producing an abundance of small particles. Given those challenges, we suggest instead that the observations are most commensurate with dynamical clearing due to tidal interactions with low-mass companions-very young ({approx}1 Myr) brown dwarfs or giant planets on long-period orbits.« less
  • We have imaged GM Aurigae with the Hubble Space Telescope , detected its disk in scattered light at 1400 and 1650 Å, and compared these with observations at 3300 Å, 5550 Å, 1.1 μ m, and 1.6 μ m. The scattered light increases at shorter wavelengths. The radial surface brightness profile at 3300 Å shows no evidence of the 24 au radius cavity that has been previously observed in submillimeter observations. Comparison with dust grain opacity models indicates that the surface of the entire disk is populated with submicron grains. We have compiled a spectral energy distribution from 0.1 μmore » m to 1 mm and used it to constrain a model of the star + disk system that includes the submillimeter cavity using the Monte Carlo radiative transfer code by Barbara Whitney. The best-fit model image indicates that the cavity should be detectable in the F330W bandpass if the cavity has been cleared of both large and small dust grains, but we do not detect it. The lack of an observed cavity can be explained by the presence of submicron grains interior to the submillimeter cavity wall. We suggest one explanation for this that could be due to a planet of mass <9 M {sub J} interior to 24 au. A unique cylindrical structure is detected in the far-UV data from the Advanced Camera for Surveys/Solar Blind Channel. It is aligned along the system semiminor axis, but does not resemble an accretion-driven jet. The structure is limb brightened and extends 190 ± 35 au above the disk midplane. The inner radius of the limb brightening is 40 ± 10 au, just beyond the submillimeter cavity wall.« less