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Post Info TOPIC: HD 169142
Blobrana


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Posts: 131433
Date:
2MASS J18242978-2946492
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Title: Detailed structure of the outer disk around HD 169142 with polarised light in H-band
Author: Munetake Momose, Ayaka Morita, Misato Fukagawa, Takayuki Muto, Taku Takeuchi, Jun Hashimoto, Mitsuhiko Honda, Tomoyuki Kudo, Yoshiko K. Okamoto, Kazuhiro D. Kanagawa, Hidekazu Tanaka, Carol A. Grady, Michael L. Sitko, Eiji Akiyama, Thayne Currie, Katherine B. Follette, Satoshi Mayama, Nobuhiko Kusakabe, Lyu Abe, Wolfgang Brandner, Timothy D. Brandt, Joseph C. Carson, Sebastian Egner, Markus Feldt, Miwa Goto, Olivier Guyon, Yutaka Hayano, Masahiko Hayashi, Saeko S. Hayashi, Thomas Henning, Klaus W. Hodapp, Miki Ishii, Masanori Iye, Markus Janson, Ryo Kandori, Gillian R. Knapp, Masayuki Kuzuhara, Jungmi Kwon, Taro Matsuo, Michael W. McElwain, Shoken Miyama, Jun-Ichi Morino, Amaya Moro-Martin, Tetsuo Nishimura, Tae-Soo Pyo, Eugene Serabyn, Takuya Suenaga, Hiroshi Suto, Ryuji Suzuki, Yasuhiro H. Takahashi, et al. (12 additional authors not shown)

Coronagraphic imagery of the circumstellar disk around HD 169142 in H-band polarised intensity (PI) with Subaru/HiCIAO is presented. The emission scattered by dust particles at the disk surface in 0.2" <= r <= 1.2", or 29 <= r <= 174 AU, is successfully detected. The azimuthally-averaged radial profile of the PI shows a double power-law distribution, in which the PIs in r=29-52 AU and r=81.2-145 AU respectively show r^{-3}-dependence. These two power-law regions are connected smoothly with a transition zone (TZ), exhibiting an apparent gap in r=40-70 AU. The PI in the inner power-law region shows a deep minimum whose location seems to coincide with the point source at \lambda = 7 mm. This can be regarded as another sign of a protoplanet in TZ. The observed radial profile of the PI is reproduced by a minimally flaring disk with an irregular surface density distribution or with an irregular temperature distribution or with the combination of both. The depletion factor of surface density in the inner power-law region (r< 50 AU) is derived to be <= 0.16 from a simple model calculation. The obtained PI image also shows small scale asymmetries in the outer power-law region. Possible origins for these asymmetries include corrugation of the scattering surface in the outer region, and shadowing effect by a puffed up structure in the inner power-law region.

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Blobrana


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Posts: 131433
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RE: HD 169142
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Title: Gaps in the HD169142 protoplanetary disk revealed by polarimetric imaging: Signs of ongoing planet formation?
Authors: Sascha P. Quanz (1), Henning Avenhaus (1), Esther Buenzli (2), Antonio Garufi (1), Hans Martin Schmid (1), Sebastian Wolf (3) ((1) ETH Zurich, (2) Steward Observatory, University of Arizona, (3) University of Kiel)

We present H-band VLT/NACO polarised light images of the Herbig Ae/Be star HD169142 probing its protoplanetary disk as close as ~0.1" to the star. Our images trace the face-on disk out to ~1.7" (~250 AU) and reveal distinct sub-structures for the first time: 1) the inner disk (<20 AU) appears to be depleted in scattering dust grains; 2) an unresolved disk rim is imaged at ~25 AU; 3) an annular gap extends from ~40 - 70 AU; 4) local brightness asymmetries are found on opposite sides of the annular gap. We discuss different explanations for the observed morphology among which ongoing planet formation is a tempting - but yet to be proven - one. Outside of ~85 AU the surface brightness drops off roughly r^{-3.3}, but describing the disk regions between 85-120 AU / 120-250 AU separately with power-laws r^{-2.6} / r^{-3.9} provides a better fit hinting towards another discontinuity in the disk surface. The flux ratio between the disk integrated polarised light and the central star is ~4.1 * 10^{-3}. Finally, combining our results with those from the literature, ~40% of the scattered light in the H-band appears to be polarised. Our results emphasise that HD169142 is an interesting system for future planet formation or disk evolution studies.

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Blobrana


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Title: Mid-IR imaging of the transitional disk of HD169142: Measuring the size of the gap
Authors: M. Honda, Koen Maaskant, Y. K. Okamoto, H. Kataza, M. Fukagawa, L. B. F. M. Waters, C. Dominik, A. G. G. M. Tielens, G. D. Mulders, M. Min, T. Yamashìta, T. Fujiyoshi, T. Miyata, S. Sako, I. Sakon, H. Fujiwara, T. Onaka

The disk around the Herbig Ae star HD 169142 was imaged and resolved at 18.8 and 24.5µm using Subaru/COMICS. We interpret the observations using a 2D radiative transfer model and find evidence for the presence of a large gap. The MIR images trace dust that emits at the onset of the strong rise in the spectral energy distribution (SED) at 20µm, therefore are very sensitive to the location and characteristics of the inner wall of the outer disk and its dust. We determine the location of the wall to be 23^{+3}_{-5} AU from the star. An extra component of hot dust must exist close to the star. We find that a hydrostatic optically thick inner disk does not produce enough flux in the NIR and an optically thin geometrically thick component is our solution to fit the SED. Considering the recent findings of gaps and holes in a number of Herbig Ae/Be group I disks, we suggest that such disk structures may be common in group I sources. Classification as group I should be considered a support for classification as a transitional disk, though improved imaging surveys are needed to support this speculation.

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