ALMA continuum observations of the protoplanetary disk AS 209. Evidence of multiple gaps opened by a single planet
ALMA continuum observations of the protoplanetary disk AS 209. Evidence of multiple gaps opened by a single planet
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DOI：
10.1051/0004-6361/201731978
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发表时间：
2017-11
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通讯作者：
D. Fedele;M. Tazzari;R. Booth;L. Testi;C. Clarke;I. Pascucci;Á. Kóspál;D.Semenov;S. Bruderer;T. Henning;R. I. A. D. Arcetri;I. O. Astronomy;U. Cambridge;E. Observatory;Lunar;Planetary Laboratory;The University of Arizona;K. Observatory;Research Centre in Astronomy;Earth Sciences;H. A. O. Sciences;M. F. Astronomy
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作者：
D. Fedele;M. Tazzari;R. Booth;L. Testi;C. Clarke;I. Pascucci;Á. Kóspál;D.Semenov;S. Bruderer;T. Henning;R. I. A. D. Arcetri;I. O. Astronomy;U. Cambridge;E. Observatory;Lunar;Planetary Laboratory;The University of Arizona;K. Observatory;Research Centre in Astronomy;Earth Sciences;H. A. O. Sciences;M. F. Astronomy
本文介绍了蛇夫座星星形成区原行星系统AS 209的新的高角分辨率阿尔马1.3 mm尘埃连续观测。尘埃连续辐射的特征是一个主中心核和两个位于r = 75，$au和r = 130，$au处的突出环，环之间有两个位于r = 62，$au和r = 103，$au处的间隙。这两个缺口的宽度和深度不同，内侧的缺口更窄更浅。我们使用3D辐射传输磁盘代码\textsc{dali}确定毫米尘埃颗粒的表面密度。根据我们的基准模型，内部间隙部分填充有毫米颗粒，而外部间隙基本上没有灰尘。推断的表面密度进行比较，三维流体动力学模拟（FARGO-3D）的行星盘相互作用。外层的尘埃间隙与一颗巨大的行星（$M_{\rm planet} \sim 0. 8\，M_{\rm Staturn}$）的存在是一致的;这颗行星负责差距的打开和行星轨道外缘的尘埃堆积。模拟还表明，同一颗行星可以在$r = 62\，$au处产生内部间隙。两个尘埃间隙的相对位置接近2：1共振，我们已经研究了内部间隙内第二颗行星的可能性。由此产生的表面密度（包括两个尘埃间隙的位置、宽度和深度）与观测结果一致。内隙的性质对内行星的质量（$M_{\rmplanet} <0.1\，M_{\rmJ}$）构成了强约束。在这两种情况下（单个或成对的行星），流体动力学模拟表明一个非常低的磁盘粘度（$\alpha < 10^{-4}$）。考虑到系统的年轻年龄（0.5 - 1百万年），这一结果意味着巨行星的形成发生在$\lesssim $1\，Myr的时间尺度上。
The paper presents new high angular resolution ALMA 1.3 mm dust continuum observations of the protoplanetary system AS 209 in the Ophiuchus star forming region. The dust continuum emission is characterized by a main central core and two prominent rings at $r = 75\,$au and $r = 130\,$au intervaled by two gaps at at $r = 62\,$au and $r = 103\,$au. The two gaps have different widths and depths, with the inner one being narrower and shallower. We determined the surface density of the millimeter dust grains using the 3D radiative transfer disk code \textsc{dali}. According to our fiducial model the inner gap is partially filled with millimeter grains while the outer gap is largely devoid of dust. The inferred surface density is compared to 3D hydrodynamical simulations (FARGO-3D) of planet-disk interaction. The outer dust gap is consistent with the presence of a giant planet ($M_{\rm planet} \sim 0.8\,M_{\rm Staturn}$); the planet is responsible for the gap opening and for the pile-up of dust at the outer edge of the planet orbit. The simulations also show that the same planet can give origin to the inner gap at $r = 62\,$au. The relative position of the two dust gaps is close to the 2:1 resonance and we have investigated the possibility of a second planet inside the inner gap. The resulting surface density (including location, width and depth of the two dust gaps) are in agreement with the observations. The properties of the inner gap pose a strong constraint to the mass of the inner planet ($M_{\rm planet} < 0.1\,M_{\rm J}$). In both scenarios (single or pair of planets), the hydrodynamical simulations suggest a very low disk viscosity ($\alpha < 10^{-4}$). Given the young age of the system (0.5 - 1 Myr), this result implies that the formation of giant planets occurs on a timescale of $\lesssim$ 1\,Myr.