The potential of combining MATISSE and ALMA observations: constraining the structure of the innermost region in protoplanetary discs
The potential of combining MATISSE and ALMA observations: constraining the structure of the innermost region in protoplanetary discs
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DOI：
10.1051/0004-6361/201833784
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发表时间：
2019-01
影响因子：
6.5
通讯作者：
J. Kobus;S. Wolf;R. Brunngraber
中科院分区：
文献类型：
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作者：
J. Kobus;S. Wolf;R. Brunngraber
上下文。为了研究行星形成的初始条件，获得原行星盘最内层区域的空间分辨多波长观测是至关重要的。目标。我们评估了MATISSE/VLTI和ALMA结合观测的优势，以约束附近恒星形成区域的星周盘最内层区域的尘埃的径向和垂直结构。方法。基于参数化尘埃密度分布的圆盘模型，我们应用三维辐射传输模拟得到理想的强度图。这些用于推导我们将使用MATISSE以及用CASA模拟的ALMA地图获得的相应的波长相关可见度。结果。在考虑的参数空间内，我们发现仅用MATISSE来限制中心恒星周围最内层5au的尘埃密度结构是具有挑战性的，而ALMA的观测具有合理的积分时间，使我们能够推导出圆盘表面密度的重要约束。然而，我们发现MATISSE和ALMA观测相结合可以显著改善对不同圆盘参数的估计。例如，将30分钟ALMA观测（310 GHz，角分辨率为0.03”）与MATISSE观测在L和M波段（能见度精度约为3%）相结合，可以将径向密度斜率和尘埃表面密度剖面分别限制在Δα = 0.3和Δ(α - β) = 0.15之内。对于~1%的精度，即使圆盘耀斑也可以限制在Δβ = 0.1以内。为了将标度高度限制在5 au以内，需要0.8%的M波段精度。虽然ALMA对沉降在圆盘中部的大尘粒的数量比较敏感，但我们发现大尘粒的表面密度分布对观测量的影响很小。
Context. In order to study the initial conditions of planet formation, it is crucial to obtain spatially resolved multi-wavelength observations of the innermost region of protoplanetary discs. Aims. We evaluate the advantage of combining observations with MATISSE/VLTI and ALMA to constrain the radial and vertical structure of the dust in the innermost region of circumstellar discs in nearby star-forming regions. Methods. Based on a disc model with a parameterized dust density distribution, we apply 3D radiative-transfer simulations to obtain ideal intensity maps. These are used to derive the corresponding wavelength-dependent visibilities we would obtain with MATISSE as well as ALMA maps simulated with CASA. Results. Within the considered parameter space, we find that constraining the dust density structure in the innermost 5 au around the central star is challenging with MATISSE alone, whereas ALMA observations with reasonable integration times allow us to derive significant constraints on the disc surface density. However, we find that the estimation of the different disc parameters can be considerably improved by combining MATISSE and ALMA observations. For example, combining a 30-min ALMA observation (at 310 GHz with an angular resolution of 0.03′′) for MATISSE observations in the L and M bands (with visibility accuracies of about 3%) allows the radial density slope and the dust surface density profile to be constrained to within Δα = 0.3 and Δ(α − β) = 0.15, respectively. For an accuracy of ~1% even the disc flaring can be constrained to within Δβ = 0.1. To constrain the scale height to within 5 au, M band accuracies of 0.8% are required. While ALMA is sensitive to the number of large dust grains settled to the disc midplane we find that the impact of the surface density distribution of the large grains on the observed quantities is small.