Tsukagoshi, T, Nomura, H, Muto, T et al. (10 more authors) (2022) ALMA High-resolution Multiband Analysis for the Protoplanetary Disk around TW Hya. The Astrophysical Journal, 928 (1). 49. ISSN 0004-637X
Abstract
We present a high-resolution (2.5 au) multiband analysis of the protoplanetary disk around TW Hya using Atacama Large Millimeter/submillimeter Array (ALMA) long baseline data at Bands 3, 4, 6, and 7. We aim to reconstruct a high-sensitivity millimeter continuum image and revisit the spectral index distribution. The imaging is performed by combining new ALMA data at Bands 4 and 6 with available archive data. Two methods are employed to reconstruct the images: multifrequency synthesis (MFS) and the fiducial image-oriented method, where each band is imaged separately and the frequency dependence is fitted pixel by pixel. We find that MFS imaging with a second-order Taylor expansion can reproduce the frequency dependence of the continuum emission between Bands 3 and 7 in a manner consistent with previous studies, and that it is a reasonable method for reconstructing the spectral index map. The image-oriented method provides a spectral index map consistent with the MFS imaging, but with a two times lower resolution. Mock observations of an intensity model were conducted to validate the images from the two methods. We find that the MFS imaging provides a high-resolution spectral index distribution with an uncertainty of <10%. Using the submillimeter spectrum reproduced from our MFS images, we directly calculate the optical depth, power-law index of the dust opacity coefficient (β), and dust temperature. The derived parameters are consistent with previous works, and the enhancement of β within the intensity gaps is also confirmed, supporting a deficit of millimeter-sized grains within the gaps.
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Copyright, Publisher and Additional Information: | © 2022. The Author(s). This is an open access article under the terms of the Creative Commons Attribution 4.0 International License (CC BY 4.0) (https://creativecommons.org/licenses/by/4.0/) | ||||||
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Institution: | The University of Leeds | ||||||
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Astrophysics (Leeds) | ||||||
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Depositing User: | Symplectic Publications | ||||||
Date Deposited: | 20 Apr 2022 14:10 | ||||||
Last Modified: | 20 Apr 2022 14:10 | ||||||
Status: | Published | ||||||
Publisher: | IOP Publishing | ||||||
Identification Number: | https://doi.org/10.3847/1538-4357/ac5111 | ||||||
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