In an attempt to better understand the conditions under which molecules condense onto grains in the envelopes of evolved stars, we have searched for the presence of H2O ice in the circumstellar envelopes of several evolved (OH/IR) stars. The sample of stars observed was selected on the basis of mass-loss rates, luminosities, and outflow velocities in order to cover a range of physical conditions that might affect the amount of ice present in stellar envelopes. Despite the clear presence of H2O ice around other, previously observed, evolved stars, our search in six OH/IR stars has resulted in only one clear detection, in OH 26.5 + 0.6, and the tentative detection in one other, OH 26.4-1.9. We provide column densities or upper limits for the amount of ice that is present on the grains around these stars and explore the possibility that there could be a relationship between M* or M*/L* and the H2O ice column density to explain the observations.

中文翻译：

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H[TINF]2[/TINF]O OH/IR 恒星包层中的冰

为了更好地了解分子在演化恒星包膜中凝聚成颗粒的条件，我们在几颗演化 (OH/IR) 恒星的星周包膜中寻找了 H2O 冰的存在。观测到的恒星样本是根据质量损失率、光度和流出速度选择的，以涵盖可能影响恒星包层中冰量的一系列物理条件。尽管在其他先前观察到的演化恒星周围明显存在 H2O 冰，但我们对 6 颗 OH/IR 恒星的搜索只导致了一颗清晰的探测，在 OH 26.5 + 0.6 中，而在另一颗中进行了初步探测，即 OH 26.4-1.9 .