Evolution of the radial and vertical distribution of protoplanetary disks from scattered-light observations

散射光观测中原行星盘径向和垂直分布的演化

• 批准号: 2859987
• 金额: --
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2859987
• 关键词: Evolution; radial; vertical; distribution; protoplanetary

Protoplanetary disks are the sites of planet formation. They are mainly composed by molecular gas, however, accessing the gas distribution from observations (including gas mass and its radial/vertical extension) in disks is challenging. Therefore, most of the information that we have about planets forming in disks comes from the dust that dominates the disk opacity. Observationally, we can access the distribution of micron-sized particles and pebbles (mm/cm-sized particles) trough observations of scattered-light at optical/near infrared and interferometric (sub-) millimeter observations, respectively. Due to the aerodynamical drag from the gas, pebbles are subject to radial drift and settling to the midplane in disks. For this reason, the radial and vertical extension of pebbles inferred from observations do not trace the actual gas disk distribution. However, small grains are expected to be well coupled to the gas and their distribution is close to the gas distribution. Recently, the SPHERE instrument at VLT have provided unprecedented scattered-light images of several protoplanetary disks. This PhD project aims to connect models of gas and dust evolution in protoplanetary disks under different physical conditions that can rule their evolution and compare the results with state-of-the-art SPHERE observations. I am part of an international collaboration of a large accepted program (DESTINYS), which targets 85 protoplanetary disks around T-Tauri stars in different star forming regions with different age (from ~1 to 10 million years). With the privileged access to these data, in this project we will investigate the radial and vertical distribution in protoplanetary disks as seen in scattered light and its evolution, connect to what is observed at mm-emission from powerful telescopes, such as ALMA, in order to have a better understanding of the physical mechanisms that rule the evolution of disks.There are two leading mechanisms proposed for transporting mass and angular momentum that drive global disk evolution: turbulent viscosity and Magneto-hydrodynamical (MHD) disk winds, both of them leave different imprints on the evolution of the gas disk size: while the disk is expected to expand with time in the turbulent viscosity case, the opposite happens in the case of MHD winds. On the other hand, the vertical distribution of the small grains in protoplanetary disks can provide constrains on the vertical turbulence in the disks , and with this project we will study the potential evolution of such vertical turbulence. The knowledge of what drives the evolution of protoplanetary disk is a key element to understand how planets form in these systems and to link with the large population of exoplanets observed up to day.

原行星盘是行星形成的场所。它们主要由分子气体组成，然而，从观测（包括气体质量及其径向/垂直延伸）中获得气体分布是具有挑战性的。因此，我们所拥有的关于行星在盘中形成的大部分信息都来自于主导盘不透明度的尘埃。在观测上，我们可以分别通过光学/近红外和干涉（亚）毫米观测的散射光观测来获得微米级颗粒和卵石（mm/cm级颗粒）的分布。由于来自气体的空气动力学阻力，卵石受到径向漂移和沉降到圆盘中的中平面。由于这个原因，从观测中推断出的卵石的径向和垂直延伸并不能追踪实际的气盘分布。然而，预计小颗粒与气体良好耦合，并且它们的分布接近气体分布。最近，VLT的SPHERE仪器提供了几个原行星盘的前所未有的散射光图像。这个博士项目旨在连接不同物理条件下原行星盘中气体和尘埃演化的模型，这些模型可以控制它们的演化，并将结果与最先进的SPHERE观测结果进行比较。我是一个大型公认计划（DESTINYS）的国际合作的一部分，该计划的目标是T-Tauri恒星周围的85个原行星盘，它们位于不同年龄（从~1到1000万年）的不同星星形成区域。有了这些数据的特权访问，在这个项目中，我们将调查在散射光及其演变中看到的原行星盘的径向和垂直分布，连接到强大的望远镜，如阿尔马，为了更好地理解支配盘演化的物理机制，提出了两种主要的机制来传输质量和角度驱动全球气盘演化的两种动量：湍流粘性和磁流体动力学（MHD）气盘风，它们都在气盘大小的演化上留下了不同的印记：虽然在湍流粘性情况下气盘预计会随时间膨胀，但在MHD风的情况下则相反。另一方面，小颗粒在原行星盘中的垂直分布可以对盘中的垂直湍流提供约束，并且本项目将研究这种垂直湍流的潜在演化。了解原行星盘演化的驱动力是理解行星如何在这些系统中形成的关键因素，并与迄今为止观察到的大量系外行星联系起来。