Elemental abundance retrievals in planet-forming disks: links to embedded protoplanets

在2020年代，系外行星领域将越来越多地转向行星组成研究。其中一个关键方面是将行星元素丰度与它们在盘中的形成历史联系起来。气相元素丰度比的测量（例如，形成模型需要行星形成盘中的碳/氧（C/O）来可靠地预测行星的化学成分。随着人们对行星形成的化学诊断、生物标志物以及系外行星大气检索数据和方法的快速进展越来越感兴趣，这一点越来越及时。到目前为止，在行星形成盘中，元素丰度测量的空间分辨率非常粗糙（平均丰度比在Au尺度的10秒至100秒之间），并且通过运行少数（最多100阶）复杂模型的繁琐过程来进行，这些模型基本上是手工拟合的，以各种连续谱和来自（亚）毫米望远镜（APEX，IRAM，阿尔马等）的线数据。这意味着，与系外行星研究的最新技术相比，我们对方法中的简并性、最佳数据采集以及盘中导出丰度的真实不确定性的理解很差。我们现在正在确定磁盘气体和尘埃的差距，并将嵌入的原行星与它们联系起来，越来越有信心。阿尔马使我们能够获得前所未有的~ 10金尺度的化学成分数据。这是迅速成为必要的，以适应我们的磁盘平均丰度测量技术的小尺度，研究气体在特定的原行星附近，并测试日益复杂，但约束条件差的磁盘元素组成模型。这些进展将是解锁即将到来的JWST和Ariel系外行星组成数据的关键。在这个项目中，你将有机会利用新的数据和开发方法来推进磁盘和行星组成链接的前沿。

In the 2020s, the exoplanet field will move increasingly towards planetary composition studies. One of the key aspects is to link planetary elemental abundances to their formation history in disks. Measurements of gas-phase elemental abundance ratios (e.g., C/O) in planet-forming disks are needed for formation models to reliably predict planetary chemical compositions. This is increasingly timely, with the growing interest in chemical diagnostics of planet formation, biomarkers, and rapid progress in exoplanet atmospheric retrieval data and methods. In planet-forming disks so far, elemental abundance measurements have been done with very coarse spatial resolution (average abundance ratios over 10s-100s of au scales) and through a cumbersome process of running a handful (maximum of order 100) complicated models to be fitted, essentially by hand, to a variety of continuum and line data from (sub-)millimetre telescopes (APEX, IRAM, ALMA, etc.). This means our understanding of degeneracies in the methods, optimal data acquisition, and true uncertainties in the derived abundances in disks is poor compared to the state of the art in exoplanet studies. We are now identifying gaps in disk gas and dust, and associating embedded protoplanets with them, with growing confidence. ALMA is allowing us to obtain unprecedented chemical composition data on ~10au scales. It is quickly becoming essential to adapt our disk-averaged abundance measurement techniques for small scales, to study gas in the vicinity of specific protoplanets and to test increasingly complex but poorly constrained disk elemental composition models. These advances will be key to unlocking the impending flood of JWST and Ariel exoplanet composition data. In this project, you will have an opportunity to exploit new data and develop methods to advance the cutting edge of disk and planet composition links.