Chemistry in planet-forming regions revealed by ALMA

阿塔卡马大型毫米波/亚毫米波阵列（ALMA）是智利的一架望远镜，以毫米波观察宇宙。ALMA具有在行星形成尺度上观测冷尘埃和分子气体发射的分辨率和灵敏度。这使我们能够在类似太阳系的尺度上探测附近恒星周围的行星形成环境。ALMA最近的观测显示，在附近年轻恒星周围的圆盘中，几乎无处不在地存在尘埃亚结构，其中的尘埃被引导成同心尘埃环和不对称漩涡。这种尘埃结构的一个被提出的起源是在圆盘内存在仍在形成的行星。利兹大学的研究人员最近参与了一项名为“行星形成尺度上的ALMA分子”（MAPS）的ALMA大型项目，首次在太阳系尺度上对行星形成的化学过程进行了成像（www.alma-maps.info）。这些数据揭示了丰富的化学多样性，观测到的化学亚结构通常与尘埃亚结构不一致。目前尚不清楚为什么星盘表现出如此多样的化学成分，但很可能是由于尘埃、辐射、化学和物质运输之间复杂的相互作用。要确定圆盘中化学子结构的起源，就需要开发新的原行星盘模型，将所有这些重要的物理效应结合起来。该项目将开发新的圆盘化学模型，包括尘埃演化和亚结构，径向传输和混合的影响，受到当前关于圆盘尘埃亚结构起源的理论的启发。这些模型将用于模拟观测结果，直接与MAPS ALMA大型项目的结果进行比较，并生成诊断套件，用于激励未来的ALMA提案。

The Atacama Large Millimeter/submillimeter Array (ALMA) is a telescope in Chile that observes the universe at millimeter wavelengths. ALMA has the resolution and sensitivity to observe emission from cold dust and molecular gas on planet-forming scales. This allows us to probe the planet-building environment around nearby stars on size scales similar to the Solar System. Recent observations with ALMA have revealed the almost ubiquitous presence of dust substructure in disks around nearby young stars, in which the dust has been shepherded into concentric dust rings and asymmetric vortices. One of the proposed origins of this dust structure is the presence of still-forming planets within the disk.A recent ALMA Large Program involving Leeds' researchers, titled "Molecules with ALMA on Planet-forming Scales" or MAPS, imaged for the first time, the chemistry of planet formation on Solar System size scales (www.alma-maps.info). These data revealed a wealth of chemical diversity, with observed chemical sub-structure usually not coincident with dust sub-structure. It is still not understood why disks exhibit such chemical diversity but it is likely due to the complex interplay between dust, radiation, chemistry, and transport of material.Determining the origin of chemical sub-structure in disks requires the development of new models of protoplanetary disks that incorporate all of these important physical effects. This project will develop new models of disk chemistry that include the effects of dust evolution and sub-structure, radial transport, and mixing, motivated by current theories on the origin of dust sub-structure in disks. These models will be used to simulate observations to directly compare with the results from the MAPS ALMA Large Program, and to produce suites of diagnostics that will be used to motivate future ALMA proposals.