Measuring the ratio of the gas and dust emission radii of protoplanetary disks in the Lupus star-forming region
Measuring the ratio of the gas and dust emission radii of protoplanetary disks in the Lupus star-forming region
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DOI：
10.1051/0004-6361/202039733
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发表时间：
2021-01
影响因子：
6.5
通讯作者：
E. Sanchis;L. Testi;A. Natta;S. Facchini;C. Manara;A. Miotello;B. Ercolano;T. Henning;T. Preibi
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文献类型：
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作者：
E. Sanchis;L. Testi;A. Natta;S. Facchini;C. Manara;A. Miotello;B. Ercolano;T. Henning;T. Preibi
我们进行了全面的人口统计研究的CO范围相对于尘埃的磁盘人口在狼疮云，以找到证据的尘埃演化和可能的相关性与其他磁盘属性。根据12 CO J = 2−1旋转跃迁中的气体发射和~0.89 mm处的大尘埃颗粒发射，我们将Atacama大型毫米/亚毫米阵列观测到的RCO和Rdust区域的圆盘数量增加到42个。该连续体被拟合到来自干涉建模的Nuker轮廓。CO和尘埃的大小，即包围各自总通量的一定比例的半径（例如，R68%），从建模推断。CO排放比粉尘连续体更广泛，对于整个人群和具有高完整性的子样本，R68%CO/R68%dust中值为2.5。六个磁盘，约15%的狼疮磁盘人口，具有大于4的大小比。基于热化学建模，该值只能在圆盘经历晶粒生长和径向漂移的情况下解释。这些盘没有不寻常的性质，它们的性质分布在整个星群的恒星质量（M），盘质量（Mdisk），CO和尘埃大小（RCO，Rdust）以及整个星群的质量吸积范围内。我们寻找的尺寸比和M的，Mdisk，RCO，和Rdust之间的相关性：只有一个弱的单调的关系与Rdust，这意味着尘埃演化是更突出的更紧凑的尘埃盘。缺乏强相关性是值得注意的：样本涵盖了广泛的恒星和磁盘属性，大多数磁盘具有非常相似的尺寸比。这一结果表明，大部分的磁盘人口可能表现相似，并在一个类似的演化阶段，独立于恒星和磁盘的属性。这些结果应进一步研究，因为CO和尘埃连续体之间的光学深度差可能在观测到的人口规模比中发挥重要作用。最后，我们发现CO通量和CO尺寸之间的单调相关性。大多数磁盘的结果是一致的光学厚发射和平均CO温度约为30 K，然而，温度的确切值是难以约束。
We performed a comprehensive demographic study of the CO extent relative to dust of the disk population in the Lupus clouds in order to find indications of dust evolution and possible correlations with other disk properties. We increased the number of disks of the region with measured RCO and Rdust from observations with the Atacama Large Millimeter/submillimeter Array to 42, based on the gas emission in the 12CO J = 2−1 rotational transition and large dust grains emission at ~0.89 mm. The CO integrated emission map is modeled with an elliptical Gaussian or Nuker function, depending on the quantified residuals; the continuum is fit to a Nuker profile from interferometric modeling. The CO and dust sizes, namely the radii enclosing a certain fraction of the respective total flux (e.g., R68%), are inferred from the modeling. The CO emission is more extended than the dust continuum, with a R68%CO/R68%dust median value of 2.5, for the entire population and for a subsample with high completeness. Six disks, around 15% of the Lupus disk population, have a size ratio above 4. Based on thermo-chemical modeling, this value can only be explained if the disk has undergone grain growth and radial drift. These disks do not have unusual properties, and their properties spread across the population’s ranges of stellar mass (M⋆), disk mass (Mdisk), CO and dust sizes (RCO, Rdust), and mass accretion of the entire population. We searched for correlations between the size ratio and M⋆, Mdisk, RCO, and Rdust: only a weak monotonic anticorrelation with the Rdust is found, which would imply that dust evolution is more prominent in more compact dusty disks. The lack of strong correlations is remarkable: the sample covers a wide range of stellar and disk properties, and the majority of the disks have very similar size ratios. This result suggests that the bulk of the disk population may behave alike and be in a similar evolutionary stage, independent of the stellar and disk properties. These results should be further investigated, since the optical depth difference between CO and dust continuum might play a major role in the observed size ratios of the population. Lastly, we find a monotonic correlation between the CO flux and the CO size. The results for the majority of the disks are consistent with optically thick emission and an average CO temperature of around 30 K; however, the exact value of the temperature is difficult to constrain.