van Dishoeck Ewine F, Grant S, Tabone B, van Gelder M, Francis L, Tychoniec L, Bettoni G, Arabhavi A M, Gasman D, Nazari P, Vlasblom M, Kavanagh P, Christiaens V, Klaassen P, Beuther H, Henning Th, Kamp I
Leiden Observatory, Leiden University, P. O. Box 9513, 2300 RA Leiden, The Netherlands.
Max-Planck Institut für Extraterrestrische Physik (MPE), Giessenbachstr. 1, 85748, Garching, Germany.
Faraday Discuss. 2023 Sep 20;245(0):52-79. doi: 10.1039/d3fd00010a.
Early results from the James Webb Space Telescope-Mid-InfraRed Instrument (JWST-MIRI) guaranteed time programs on protostars (JOYS) and disks (MINDS) are presented. Thanks to the increased sensitivity, spectral and spatial resolution of the MIRI spectrometer, the chemical inventory of the planet-forming zones in disks can be investigated with unprecedented detail across stellar mass range and age. Here, data are presented for five disks, four around low-mass stars and one around a very young high-mass star. The mid-infrared spectra show some similarities but also significant diversity: some sources are rich in CO, others in HO or CH. In one disk around a very low-mass star, booming CH emission provides evidence for a "soot" line at which carbon grains are eroded and sublimated, leading to a rich hydrocarbon chemistry in which even di-acetylene (CH) and benzene (CH) are detected. Together the data point to an active inner disk gas-phase chemistry that is closely linked to the physical structure (temperature, snowlines, presence of cavities and dust traps) of the entire disk and which may result in varying CO/HO abundances and high C/O ratios >1 in some cases. Ultimately, this diversity in disk chemistry will also be reflected in the diversity of the chemical composition of exoplanets.
本文展示了詹姆斯·韦布空间望远镜中红外仪器（JWST-MIRI）针对原恒星（JOYS）和星盘（MINDS）的保证时间观测项目的早期结果。得益于MIRI光谱仪灵敏度、光谱和空间分辨率的提高，能够以前所未有的详细程度研究恒星质量范围和年龄内星盘中行星形成区域的化学组成。这里展示了五个星盘的数据，其中四个围绕低质量恒星，一个围绕一颗非常年轻的高质量恒星。中红外光谱显示出一些相似性，但也存在显著差异：一些源富含CO，另一些富含HO或CH。在一颗极低质量恒星周围的一个星盘中，强烈的CH发射为一条“烟灰”线提供了证据，在这条线上碳颗粒被侵蚀和升华，导致丰富的碳氢化合物化学，甚至检测到了丁二炔（CH）和苯（CH）。这些数据共同表明，活跃的内盘气相化学与整个星盘的物理结构（温度、雪线、空洞和尘埃陷阱的存在）密切相关，在某些情况下可能导致CO/HO丰度变化以及高C/O比>1。最终，星盘化学的这种多样性也将反映在系外行星化学成分的多样性上。
