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

    Research output: Contribution to journalArticle

    Published
    • Takashi Tsukagoshi
    • Takayuki Muto
    • Hideko Nomura
    • Ryohei Kawabe
    • Kazuhiro D. Kanagawa
    • Satoshi Okuzumi
    • Shigeru Ida
    • Catherine Walsh
    • Tom J. Millar
    • Sanemichi Z. Takahashi
    • Jun Hashimoto
    • Taichi Uyama
    • Motohide Tamara

    View graph of relations

    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.

    Documents

    DOI

    Original languageEnglish
    Article numberL8
    Number of pages6
    JournalThe Astrophysical Journal. Letters
    Journal publication date06 Jun 2019
    Issue number1
    Volume878
    DOIs
    Publication statusPublished - 06 Jun 2019

    ID: 172079450