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Title: DISCOVERY OF A DISK GAP CANDIDATE AT 20 AU IN TW HYDRAE

Abstract

We present a new Subaru/HiCIAO high-contrast H-band polarized intensity (PI) image of a nearby transitional disk associated with TW Hydrae. The scattered light from the disk was detected from 0.″ 2 to 1.″ 5 (11–81 AU) and the PI image shows a clear axisymmetric depression in PI at ∼0.″ 4 (∼20 AU) from the central star, similar to the ∼80 AU gap previously reported from Hubble Space Telescope images. The azimuthal PI profile also shows that the disk beyond 0.″ 2 is almost axisymmetric. We discuss two possible scenarios explaining the origin of the PI depression: (1) a gap structure may exist at ∼20 AU from the central star because of a shallow slope seen in the PI profile, and (2) grain growth may be occurring in the inner region of the disk. Multi-band observations at near-infrared and millimeter/submillimeter wavelengths play a complementary role in investigating dust opacity and may help reveal the origin of the gap more precisely.

Authors:
; ;  [1];  [2]; ;  [3]; ;  [4];  [5];  [6]; ;  [7];  [8];  [9];  [10]; ;  [11];  [12];  [13];  [14] more »; « less
  1. National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588 (Japan)
  2. Division of Liberal Arts, Kogakuin University, 1-24-2, Nishi-Shinjuku, Shinjuku-ku, Tokyo 163-8677 (Japan)
  3. Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1, Oklahoma, Ookayama, Meguro-ko, Tokyo 152-8551 (Japan)
  4. Department of Physics and Astronomy, The University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States)
  5. College of Science, Ibaraki University, 2-1-1, Bunkyo, Mito, Ibaraki 310-8512 (Japan)
  6. Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
  7. Subaru Telescope, National Astronomical Observatory of Japan, 650, North A'ohoku Place, Hilo, HI 96720 (United States)
  8. Eureka Scientific, 2452 Delmer, Suite 100, Oakland, CA 96002 (United States)
  9. Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China)
  10. Department of Astronomy, Stockholm University, AlbaNova University Center, Stockholm, SE-106 91 (Sweden)
  11. Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)
  12. Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 (United States)
  13. The Center for the Promotion of Integrated Sciences, The Graduate University for Advance Studies, Shonan International Village, Hayama-cho, Miura-gun, Kanagawa 240-0115 (Japan)
  14. Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland)
Publication Date:
OSTI Identifier:
22518830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 802; 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; AXIAL SYMMETRY; COSMIC DUST; GRAIN GROWTH; IMAGES; INTERSTELLAR GRAINS; OPACITY; PROTOPLANETS; SPACE; STARS; TELESCOPES; VISIBLE RADIATION

Citation Formats

Akiyama, E., Kusakabe, N., Kandori, R., Muto, T., Kataoka, A., Kuzuhara, M., Hashimoto, J., Wisniewski, J., Tsukagoshi, T., Kwon, J., Kudo, T., Currie, T., Grady, C. A., Takami, M., Janson, M., Henning, T., Carson, J. C., Sitko, M. L., Mayama, S., Thalmann, C., E-mail: eiji.akiyama@nao.ac.jp, and and others. DISCOVERY OF A DISK GAP CANDIDATE AT 20 AU IN TW HYDRAE. United States: N. p., 2015. Web. doi:10.1088/2041-8205/802/2/L17.
Akiyama, E., Kusakabe, N., Kandori, R., Muto, T., Kataoka, A., Kuzuhara, M., Hashimoto, J., Wisniewski, J., Tsukagoshi, T., Kwon, J., Kudo, T., Currie, T., Grady, C. A., Takami, M., Janson, M., Henning, T., Carson, J. C., Sitko, M. L., Mayama, S., Thalmann, C., E-mail: eiji.akiyama@nao.ac.jp, & and others. DISCOVERY OF A DISK GAP CANDIDATE AT 20 AU IN TW HYDRAE. United States. doi:10.1088/2041-8205/802/2/L17.
Akiyama, E., Kusakabe, N., Kandori, R., Muto, T., Kataoka, A., Kuzuhara, M., Hashimoto, J., Wisniewski, J., Tsukagoshi, T., Kwon, J., Kudo, T., Currie, T., Grady, C. A., Takami, M., Janson, M., Henning, T., Carson, J. C., Sitko, M. L., Mayama, S., Thalmann, C., E-mail: eiji.akiyama@nao.ac.jp, and and others. Wed . "DISCOVERY OF A DISK GAP CANDIDATE AT 20 AU IN TW HYDRAE". United States. doi:10.1088/2041-8205/802/2/L17.
@article{osti_22518830,
title = {DISCOVERY OF A DISK GAP CANDIDATE AT 20 AU IN TW HYDRAE},
author = {Akiyama, E. and Kusakabe, N. and Kandori, R. and Muto, T. and Kataoka, A. and Kuzuhara, M. and Hashimoto, J. and Wisniewski, J. and Tsukagoshi, T. and Kwon, J. and Kudo, T. and Currie, T. and Grady, C. A. and Takami, M. and Janson, M. and Henning, T. and Carson, J. C. and Sitko, M. L. and Mayama, S. and Thalmann, C., E-mail: eiji.akiyama@nao.ac.jp and and others},
abstractNote = {We present a new Subaru/HiCIAO high-contrast H-band polarized intensity (PI) image of a nearby transitional disk associated with TW Hydrae. The scattered light from the disk was detected from 0.″ 2 to 1.″ 5 (11–81 AU) and the PI image shows a clear axisymmetric depression in PI at ∼0.″ 4 (∼20 AU) from the central star, similar to the ∼80 AU gap previously reported from Hubble Space Telescope images. The azimuthal PI profile also shows that the disk beyond 0.″ 2 is almost axisymmetric. We discuss two possible scenarios explaining the origin of the PI depression: (1) a gap structure may exist at ∼20 AU from the central star because of a shallow slope seen in the PI profile, and (2) grain growth may be occurring in the inner region of the disk. Multi-band observations at near-infrared and millimeter/submillimeter wavelengths play a complementary role in investigating dust opacity and may help reveal the origin of the gap more precisely.},
doi = {10.1088/2041-8205/802/2/L17},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 802,
place = {United States},
year = {Wed Apr 01 00:00:00 EDT 2015},
month = {Wed Apr 01 00:00:00 EDT 2015}
}
  • We present a 0.5-2.2 {mu}m scattered light spectrum of the circumstellar disk around TW Hya from a combination of spatially resolved Hubble Space Telescope STIS spectroscopy and NICMOS coronagraphic images of the disk. We investigate the morphology of the disk at distances >40 AU over this wide range of wavelengths, and identify the presence of a depression in surface brightness at {approx}80 AU that could be caused by a gap in the disk. Additionally, we quantify the surface brightness, azimuthal symmetry, and spectral character of the disk as a function of radius. Our analysis shows that the scattering efficiency ofmore » the dust is largely neutral to blue over the observed wavelengths. We model the disk as a steady {alpha}-disk with an ad hoc gap structure. The thermal properties of the disk are self-consistently calculated using a three-dimensional radiative transfer code that uses ray tracing to model the heating of the disk interior and scattered light images. We find a good fit to the data over a wide range of distances from the star if we use a model disk with a partially filled gap of 30% depth at 80 AU and with a self-similar truncation knee at 100 AU. The origin of the gap is unclear, but it could arise from a transition in the nature of the disk's dust composition or the presence of a planetary companion. Based on scalings to previous hydrodynamic simulations of gap-opening criteria for embedded proto-planets, we estimate that a planetary companion forming the gap could have a mass between 6 and 28 M{sub Circled-Plus }.« less
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