arXiv 1709.021482017-09astro-ph.SRastro-ph.EP

太阳系尺度下观测原行星盘亮度不对称性的限制

Constraints on observing brightness asymmetries in protoplanetary disks at solar system scale

Robert Brunngräber, Sebastian Wolf

DOI：: 10.1051/0004-6361/201731907

摘要：

我们已经量化了在中红外波长范围内的超大型望远镜干涉仪（VLTI）检测局部亮度不对称性的潜在能力。这项研究的动机是需要评估理论模型的行星形成的直接观察的原行星在早期的进化阶段，当他们仍然嵌入在他们的主机磁盘。到目前为止，只有少数半长轴为20-50天文单位的嵌入式候选原行星被发现。由于它们与中心恒星的角距很小，只有长基线干涉测量法才能提供角分辨能力来检测附近恒星形成区域太阳系尺度下原行星的盘不对称性。特别是，红外观测是至关重要的，直接观察散射的恒星辐射和热再发射附近嵌入的同伴。为此，我们进行了辐射转移模拟计算的热再发射和散射恒星通量从一个原行星盘托管嵌入的同伴。在此基础上，计算了在VLTI的L、M和N波段工作的未来波束组合器MATISSE的观测值。我们发现，嵌入式源的中心恒星的流量比可以低至0.5至0.6%的检测在一个可行的显着性水平，由于在嵌入式源附近的加热尘埃。此外，我们发现，检测的可能性是最高的源在中等距离$r\approx2$ AU和磁盘质量不高于$\approx10^{-4}$ M $_{\odot}$。

英文摘要：

We have quantified the potential capabilities of detecting local brightness asymmetries in circumstellar disks with the Very Large Telescope Interferometer (VLTI) in the mid-infrared wavelength range. The study is motivated by the need to evaluate theoretical models of planet formation by direct observations of protoplanets at early evolutionary stages, when they are still embedded in their host disk. Up to now, only a few embedded candidate protoplanets have been detected with semi-major axes of 20-50 au. Due to the small angular separation from their central star, only long-baseline interferometry provides the angular resolving power to detect disk asymmetries associated to protoplanets at solar system scales in nearby star-forming regions. In particular, infrared observations are crucial to observe scattered stellar radiation and thermal re-emission in the vicinity of embedded companions directly. For this purpose we performed radiative transfer simulations to calculate the thermal re-emission and scattered stellar flux from a protoplanetary disk hosting an embedded companion. Based on that, visibilities and closure phases are calculated to simulate observations with the future beam combiner MATISSE, operating at the L, M and N bands at the VLTI. We find that the flux ratio of the embedded source to the central star can be as low as 0.5 to 0.6 % for a detection at a feasible significance level due to the heated dust in the vicinity of the embedded source. Furthermore, we find that the likelihood for detection is highest for sources at intermediate distances $r\approx2$-$5$ au and disk masses not higher than $\approx10^{-4}$ M$_{\odot}$.

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