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

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，通过观测(包括气体质量及其径向/垂直延伸)来获取气体在圆盘中的分布是具有挑战性的。因此，我们掌握的关于行星在盘中形成的大部分信息都来自于主宰盘中不透明度的尘埃。在观测上，我们可以分别通过光学/近红外散射光观测和干涉(亚)毫米观测来获得微米级颗粒和卵石(毫米/厘米级颗粒)的分布。由于气体的空气动力学阻力，鹅卵石在圆盘中受到径向漂移和向中面沉降的影响。出于这个原因，从观测中推断出的鹅卵石的径向和垂直延伸并不追踪实际的气盘分布。然而，小颗粒预计会与气体很好地耦合，它们的分布接近气体分布。最近，VLT的球面仪器提供了史无前例的几个原行星盘的散射光图像。这个PHD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球体观测进行比较。我是一个被接受的大型计划(Destinys)的国际合作的一部分，该计划针对的是T-Tauri恒星周围不同恒星形成区域的85个原行星盘，这些恒星形成区域的年龄不同(从~1百万到1000万年)。有了这些数据的特权，在这个项目中，我们将研究在散射光中看到的原行星盘的径向和垂直分布及其演化，连接到从强大的望远镜，如ALMA，在毫米发射观察到的东西，以便更好地了解支配盘演化的物理机制。有两种主要的机制被提出来传输驱动全球盘演化的质量和角动量：湍流粘性和磁流体(MHD)盘风，它们都在气体盘大小的演化中留下了不同的印记：虽然在湍流粘性的情况下，盘预计会随着时间而膨胀，在MHD风的情况下，情况正好相反。另一方面，原行星圆盘中小颗粒的垂直分布可以对圆盘中的垂直湍流提供约束，本项目将研究这种垂直湍流的潜在演化。了解是什么推动了原行星盘的演化，是理解这些系统中行星是如何形成的，并与迄今为止观察到的大量系外行星相联系的关键要素。

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.