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Discovery of An au-scale Excess in Millimeter Emission from the Protoplanetary Disk around TW Hya

Tsukagoshi, Takashi and Muto, Takayuki and Nomura, Hideko and Kawabe, Ryohei and Kanagawa, Kazuhiro D. and Okuzumi, Satoshi and Ida, Shigeru and Walsh, Catherine and Millar, Tom J. and Takahashi, Sanemichi Z. and Hashimoto, Jun and Uyama, Taichi and Tamura, Motohide (2019) Discovery of An au-scale Excess in Millimeter Emission from the Protoplanetary Disk around TW Hya. Astrophysical Journal Letters, 878 (1). Art. No. L8. ISSN 2041-8213. doi:10.3847/2041-8213/ab224c.

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We report the detection of an excess in dust continuum emission at 233 GHz (1.3 mm in wavelength) in the protoplanetary disk (PPD) around TW Hya revealed through high-sensitivity observations at ~3 au resolution with the Atacama Large Millimeter/submillimeter Array. The sensitivity of the 233 GHz image has been improved by a factor of 3 with regard to that of our previous cycle 3 observations. The overall structure is mostly axisymmetric, and there are apparent gaps at 25 and 41 au as previously reported. The most remarkable new finding is a few astronomical-unit-scale excess emission in the southwest part of the PPD. The excess emission is located at 52 au from the disk center and is 1.5 times brighter than the surrounding PPD at a significance of 12σ. We performed a visibility fitting to the extracted emission after subtracting the axisymmetric PPD emission and found that the inferred size and the total flux density of the excess emission are 4.4 × 1.0 au and 250 μJy, respectively. The dust mass of the excess emission corresponds to 0.03 M⊕ if a dust temperature of 18 K is assumed. Because the excess emission can also be marginally identified in the Band 7 image at almost the same position, the feature is unlikely to be a background source. The excess emission can be explained by a dust clump accumulated in a small elongated vortex or a massive circumplanetary disk around a Neptune-mass-forming planet.

Item Type:Article
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URLURL TypeDescription Paper
Tsukagoshi, Takashi0000-0002-6034-2892
Nomura, Hideko0000-0002-7058-7682
Kawabe, Ryohei0000-0002-8049-7525
Kanagawa, Kazuhiro D.0000-0001-7235-2417
Okuzumi, Satoshi0000-0002-1886-0880
Ida, Shigeru0000-0001-9564-6186
Walsh, Catherine0000-0001-6078-786X
Millar, Tom J.0000-0001-5178-3656
Takahashi, Sanemichi Z.0000-0003-3038-364X
Uyama, Taichi0000-0002-6879-3030
Tamura, Motohide0000-0002-6510-0681
Alternate Title:Discovery of an au-scale excess in millimeter emission of TW Hya
Additional Information:© 2019 The American Astronomical Society. Received 2019 March 25; revised 2019 May 11; accepted 2019 May 17; published 2019 June 6. This Letter makes use of the following ALMA data: ADS/JAO.ALMA#2017.1.00520.S and 2016.1.00842.S. We also use the following public ALMA archive data: ADS/JAO.ALMA#2015.1.00308.S, 2015.1.00686.S, 2016.1.00229.S, 2016.1.00311.S, 2016.1.00440.S, 2016.1.00464.S, 2016.1.00629.S, and 2016.1.01495.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. A part of the data analysis was carried out on the common-use data analysis computer system at the Astronomy Data Center of NAOJ. This work was supported by JSPS KAKENHI grant Nos. 17K14244, 17H01103, 18H05441, and 19K03932. T.J.M. thanks STFC for support under grant reference ST/P000321/1. C.W. acknowledges financial support from STFC (grant reference ST/R000549/1) and the University of Leeds. Facility: ALMA. - Software: astropy, CASA.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Japan Society for the Promotion of Science (JSPS)17K14244
Japan Society for the Promotion of Science (JSPS)17H01103
Japan Society for the Promotion of Science (JSPS)18H05441
Japan Society for the Promotion of Science (JSPS)19K03932
Science and Technology Facilities Council (STFC)ST/P000321/1
Science and Technology Facilities Council (STFC)ST/R000549/1
University of LeedsUNSPECIFIED
Subject Keywords:protoplanetary disks – stars: individual (TW Hya)
Issue or Number:1
Record Number:CaltechAUTHORS:20190607-125258573
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Official Citation:Takashi Tsukagoshi et al 2019 ApJL 878 L8
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96203
Deposited By: Tony Diaz
Deposited On:07 Jun 2019 21:28
Last Modified:02 Mar 2023 22:05

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