The REASONS Survey: Resolved Millimeter Observations of a Large Debris Disk around the Nearby F Star HD 170773
The REASONS Survey: Resolved Millimeter Observations of a Large Debris Disk around the Nearby F Star HD 170773
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DOI：
10.3847/1538-4357/ab2b98
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发表时间：
2019-06
期刊：
影响因子：
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通讯作者：
A. G. Sepulveda;L. Matrà;G. Kennedy;C. D. Burgo;K. Öberg;D. Wilner;S. Marino;M. Booth;J. Carpente
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文献类型：
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作者：
A. G. Sepulveda;L. Matrà;G. Kennedy;C. D. Burgo;K. Öberg;D. Wilner;S. Marino;M. Booth;J. Carpente
碎片盘是太阳系外类似于我们自己的柯伊伯带，它们在至少17%的附近类太阳恒星周围被探测到。圆盘的形态和动力学编码了它的历史信息，以及系统内任何系外行星的历史信息。我们利用阿塔卡马大型毫米/亚毫米阵列（ALMA）对F5V恒星HD 170773周围的碎片盘进行了1.3毫米的观测。我们通过马尔可夫链蒙特卡罗方法对干涉可见性进行前向建模，对面环成像并确定其基本参数。利用对称高斯表面密度剖面，我们发现了一个71±4 au宽的带，半径为au，与其他大多数毫米分辨率的带相比，这是一个相对较大的半径。这使得HD 170773成为围绕a和F恒星的四个圆盘的一部分，其半径比最近报道的星子带半径-恒星光度关系所预期的要大。已知其中两个系统拥有直接成像的巨行星，这可能表明大带和长周期巨行星的存在之间存在联系。我们还设定了系统中CO和CN气体存在的上限，这意味着构成该带的系外彗星的CO和HCN冰质量分数分别<77%和<3%。这与太阳系彗星和其他系外彗星带一致。
Debris disks are extrasolar analogs to our own Kuiper Belt and they are detected around at least 17% of nearby Sun-like stars. The morphology and dynamics of a disk encode information about its history, as well as that of any exoplanets within the system. We used the Atacama Large Millimeter/submillimeter Array (ALMA) to obtain 1.3 mm observations of the debris disk around the nearby F5V star HD 170773. We image the face-on ring and determine its fundamental parameters by forward-modeling the interferometric visibilities through a Markov Chain Monte Carlo approach. Using a symmetric Gaussian surface density profile, we find a 71 ± 4 au wide belt with a radius of au, a relatively large radius compared with most other millimeter-resolved belts around late A/early F type stars. This makes HD 170773 part of a group of four disks around A and F stars with radii larger than expected from the recently reported planetesimal belt radius—stellar luminosity relation. Two of these systems are known to host directly imaged giant planets, which may point to a connection between large belts and the presence of long-period giant planets. We also set upper limits on the presence of CO and CN gas in the system, which imply that the exocomets that constitute this belt have CO and HCN ice mass fractions of <77% and <3%, respectively. This is consistent with solar system comets and other exocometary belts.