A mid-IR interferometric survey with MIDI/VLTI: resolving the second-generation protoplanetary disks around post-AGB binaries
A mid-IR interferometric survey with MIDI/VLTI: resolving the second-generation protoplanetary disks around post-AGB binaries
复制标题
DOI：
10.1051/0004-6361/201629161
复制
发表时间：
2017-03-01
影响因子：
6.5
通讯作者：
Waters, L. B. F. M.
中科院分区：
文献类型：
--
作者：
Hillen, M.;Van Winckel, H.;Waters, L. B. F. M.
我们对一类特定的后渐近巨分支（后AGB）双星的星周环境进行了中红外干涉测量。对于这个类的存在一个紧凑的尘埃盘已被假定的基础上，各种空间未解决的测量。目的是直接确定N带发射的角度范围，并解决紧凑的拱星结构。我们的干涉测量是用VLTI上的ECO 2仪器进行的。在总共19个不同的系统进行了观察，使用可变的基线配置。结合在一个单一的波长在10.7 μ m的所有vibrium，我们拟合两个参数模型的数据：一个统一的磁盘和环模型模仿温度梯度。我们比较了我们的观测的整个样本，与合成数据计算网格的辐射传输模型的被动照射磁盘在流体静力学平衡。这些模型的计算与Monte Carlo代码，已被广泛应用于描述周围的年轻恒星天体（YSO）的原行星盘的结构。空间分辨的观测结果表明，我们的大多数目标集群紧密地在距离无关的尺寸-颜色图，并具有非常紧凑的N带发射区域。N带发射区的典型均匀盘直径约为40 μ s，对应的典型亮温为400-600 K。分辨出的物体在干涉观测量和光谱能量分布上显示出非常相似的特征。因此，目标周围的磁盘的物理属性必须相似。我们的研究结果进行了讨论，根据最近发表的样本研究的YSO周围的次级盘的定量比较后AGB星周围的YSO。结论。我们的高角分辨率的调查进一步证实了磁盘的性质的拱星结构目前广泛的后AGB双星。原行星盘模型的网格很好地覆盖了观测到的物体。就像年轻的恒星一样，空间分辨的N波段发射区域由盘的热内缘决定。后AGB和原行星盘之间的持续比较将有助于理解晶粒生长和盘的演化过程，并限制行星形成理论。这些第二代盘是中等质量恒星双星演化理论中重要的缺失成分。
We present a mid-IR interferometric survey of the circumstellar environment of a specific class of post-asymptotic giant branch (post-AGB) binaries. For this class the presence of a compact dusty disk has been postulated on the basis of various spatially unresolved measurements. The aim is to determine the angular extent of the N-band emission directly and to resolve the compact circumstellar structures.Methods. Our interferometric survey was performed with the MIDI instrument on the VLTI. In total 19 different systems were observed using variable baseline configurations. Combining all the visibilities at a single wavelength at 10.7 mu m, we fitted two parametric models to the data: a uniform disk and a ring model mimicking a temperature gradient. We compared our observables of the whole sample, with synthetic data computed from a grid of radiative transfer models of passively irradiated disks in hydrostatic equilibrium. These models are computed with a Monte Carlo code that has been widely applied to describe the structure of protoplanetary disks around young stellar objects (YSO).Results. The spatially resolved observations show that the majority of our targets cluster closely together in the distance-independent size-colour diagram, and have extremely compact N-band emission regions. The typical uniform disk diameter of the N-band emission region is similar to 40mas, which corresponds to a typical brightness temperature of 400-600 K. The resolved objects display very similar characteristics in the interferometric observables and in the spectral energy distributions. Therefore, the physical properties of the disks around our targets must be similar. Our results are discussed in the light of recently published sample studies of YSOs to compare quantitatively the secondary discs around post-AGB stars to the ones around YSOs.Conclusions. Our high-angular-resolution survey further confirms the disk nature of the circumstellar structures present around wide post-AGB binaries. The grid of protoplanetary disk models covers very well the observed objects. Much like for young stars, the spatially resolved N-band emission region is determined by the hot inner rim of the disk. Continued comparisons between post-AGB and protoplanetary disks will help to understand grain growth and disk evolution processes, and to constrain planet formation theories. These second-generation disks are an important missing ingredient in binary evolution theory of intermediate-mass stars.