JWST-MIRI对NGC 1977受辐照盘物质损失的多维度观测
JWST-MIRI's multi-dimensional view of mass loss in the irradiated disks of NGC 1977
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中文总结 AI 辅助
本研究利用JWST/MIRI观测NGC 1977中7个受中等强度FUV辐照的原行星盘，表征其分子与原子发射特征，分析不同距离下的物质损失机制，填补了强辐照与局域盘环境间的研究空白。
中文摘要 AI 辅助
人们认为，在包含大质量恒星的区域中，原行星盘的演化以及由此产生的行星形成结果会发生显著改变。猎户座星云团（ONC）中的极端案例证明了外部辐照（FUV≳10⁴ G₀）对盘演化的影响，但中等强度环境的观测约束仍然较少。我们展示了JWST/MIRI中分辨率光谱（MRS）对NGC 1977中7个原行星盘（proplyd）的观测结果，这些盘受到来自B1V型恒星猎户座42星（42 Ori）的10³-10⁵ G₀强度外部FUV场照射。我们表征了分子（H₂）和原子（例如[Ne II]、[Ar II]、HI）物种的发射，在部分案例中，MIRI揭示了追踪原行星盘电离前沿和星风的延展发射。距离42 Ori最近的盘KCFF#1正经历极端物质损失，表现为一条数千天文单位长的尘埃尾，且缺乏清晰的H₂或HI发射，表明其处于消散的晚期阶段。其余6个盘表现出双温组分的H₂发射（500–700 K和1000–1500 K），可能分别追踪盘的分子层和光致蒸发星风，同时还存在HI谱线，用于估计物质吸积率。对比宿主恒星相似的KCFF#2和#6时，距离42 Ori更近的KCFF#2以外驱物质损失为主，存在延展的分子和原子发射；而KCFF#6仅表现出延展的H₂发射，吸积和外部物质损失的贡献大致相当。尽管样本量较小，这项工作展示了JWST/MIRI如何评估环境对盘演化的影响，而NGC 1977则填补了ONC中强辐照盘与更局域盘族之间的空白。
英文摘要
The evolution of protoplanetary disks, and consequently the outcomes of planet formation, are thought to be significantly altered in regions containing massive stars. Extreme cases in the Orion Nebula Cluster (ONC) demonstrate the impact of external irradiation (FUV$\gtrsim10^{4}$ G$_{0}$) on disk evolution, but intermediate environments remain less observationally constrained. We present JWST/MIRI Medium Resolution Spectroscopy (MRS) observations of seven proplyds in NGC 1977 exposed to an external FUV field of $10^{3}-10^{5}$ G$_{0}$ from the B1V star 42 Orionis (42 Ori). We characterize emission from molecular (H$_{2}$) and atomic (e.g., [Ne II], [Ar II], HI) species, and in some cases, MIRI reveals extended emission tracing the proplyd ionization front and wind. The closest disk to 42 Ori, KCFF#1, is undergoing extreme mass loss, traced by a 1000s-of-au-long dusty tail, and lacks clear H$_{2}$ or HI emission, indicating an advanced stage of dispersal. The remaining six disks exhibit two-temperature components of H$_{2}$ emission (500--700 K and 1000--1500 K), likely tracing the disk molecular layer and a photoevaporative wind, alongside HI lines which are used to estimate mass accretion rates. When comparing KCFF#2 and #6, which have similar host stars, KCFF#2 (closer to 42 Ori) is dominated by externally driven mass loss, with extended molecular and atomic emission, whereas KCFF#6 only shows extended H$_{2}$ emission, with roughly equal contributions from accretion and external mass loss. While the sample is small, this work demonstrates how JWST/MIRI can assess environmental impacts on disk evolution, with NGC 1977 bridging strongly irradiated disks in the ONC and the more local population.
