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Effects of the grain temperature distribution on the organic chemistry of protostellar envelopes
Astronomy & Astrophysics ( IF 5.4 ) Pub Date : 2024-12-18 , DOI: 10.1051/0004-6361/202451858
Juris Kalvāns, Juris Freimanis

Context. Dust grains in circumstellar envelopes are likely to have a spread-out temperature distribution.Aims. We investigate how trends in the temperature distribution between small and large grains affect the hot-corino chemistry of complex organic molecules (COMs) and warm carbon-chain chemistry (WCCC).Methods. A multi-grain multi-layer astrochemical code with an advanced treatment of the surface chemistry was used with three grain-temperature trends: a grain temperature proportional to the grain radius to the power -1/6 (Model M-1/6), to 0 (M0), and to 1/6 (M1/6). The cases of hot-corino chemistry and WCCC were investigated for a total of six models. The essence of these changes is that the main ice reservoir (small grains) has a higher (M-1/6) or lower (M1/6) temperature than the surrounding gas.Results. The chemistry of COMs agrees better with observations in models M-1/6 and M1/6 than in Model M0. Model M-1/6 agrees best for WCCC because earlier mass-evaporation of methane ice from small grains induces the WCCC phenomenon at lower temperatures.Conclusions. Models considering several grain populations with different temperatures reproduce the circumstellar chemistry more precisely.

中文翻译:


晶温分布对原恒星包层有机化学的影响



上下文。星际包络中的尘埃颗粒可能具有分散的温度分布。目标。我们研究了小晶粒和大晶粒之间温度分布的趋势如何影响复杂有机分子 (COM) 的热冠状化学和暖碳链化学 (WCCC)。方法。使用具有高级表面化学处理的多晶多层天体化学代码,具有三种晶粒温度趋势:晶粒温度与晶粒半径成正比,功率为 -1/6(型号 M-1/6)、0 (M0) 和 1/6 (M1/6)。共调查了 6 个模型的热冠状化学和 WCCC 病例。这些变化的本质是主冰储层(小颗粒)的温度高于周围气体 (M-1/6) 或低于 (M1/6)。结果。COM 的化学性质与模型 M-1/6 和 M1/6 中的观测结果比模型 M0 中的观察结果更吻合。M-1/6 型最适合 WCCC,因为小颗粒中甲烷冰的早期质量蒸发在较低温度下会引起 WCCC 现象。结论。考虑具有不同温度的几个颗粒群的模型可以更精确地再现星周化学。
更新日期:2024-12-19