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arXiv · 1811.10365

High-Resolution ALMA Observations of HD100546: Asymmetric Circumstellar Ring, and Circumplanetary Disk Upper Limits

J. E. Pineda·J. Szulágyi·S. P. Quanz·E. F. van Dishoeck·A. Garufi·F. Meru·G. D. Mulders·L. Testi·M. R. Meyer·M. Reggiani
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Abstract

We present long baseline Atacama Large Millimeter/submillimeter Array (ALMA) observations of the 870$\,μ$m dust continuum emission and CO (3-2) from the protoplanetary disk around the Herbig Ae/Be star HD 100546, which is one of the few systems claimed to have two young embedded planets. These observations achieve a resolution of 4 au (3.8 mas), an rms noise of 66$μ$Jy/beam, and reveal an asymmetric ring between $\sim$20-40 au with largely optically thin dust continuum emission. This ring is well fit by two concentric and overlapping Gaussian rings of different widths and a Vortex. In addition, an unresolved component is detected at a position consistent with the central star, which may trace the central inner disk ($<$2au in radius). We report a lack of compact continuum emission at the positions of both claimed protoplanets. We use this result to constrain the circumplanetary disk (CPD) mass and size of 1.44M$_{\rm Earth}$ and 0.44au in the optically thin and thick regime, respectively, for the case of the previously directly imaged protoplanet candidate at $\sim$55 au (HD100546 b). We compare these empirical CPD constraints to previous numerical simulations. This suggests that HD100546 b is inconsistent with several planet accretion models, while gas-starved models are also still compatible. We estimate the planetary mass as 1.65 M$_J$ by using the relation between planet, circumstellar, and circumplanetary masses derived from numerical simulations. Finally, the CO integrated intensity map shows a possible spiral arm feature that would match the spiral features identified in Near-Infrared scattered light polarized emission, which suggests a real spiral feature in the disk surface that needs to be confirmed with further observations.

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J. E. Pineda, J. Szulágyi, S. P. Quanz, E. F. van Dishoeck, A. Garufi, F. Meru, G. D. Mulders, L. Testi, M. R. Meyer, M. Reggiani. 2018-11-26. High-Resolution ALMA Observations of HD100546: Asymmetric Circumstellar Ring, and Circumplanetary Disk Upper Limits. https://doi.org/10.3847/1538-4357%2Faaf389

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