Detection of solid methanol toward W33A
Detection of solid methanol toward W33A
复制标题
检测固体甲醇对 W33A 的影响
DOI：
--
复制
发表时间：
1991
期刊：
影响因子：
--
通讯作者：
W. Schutte
中科院分区：
文献类型：
--
作者：
R. Grim;F. Baas;J. Greenberg;T. Geballe;W. Schutte
最近在 W33A 光谱中检测到的 3.53 微米处的吸收特征被指定为甲醇 (CH3OH)。其光学深度意味着，在迄今为止观察到的 W33A 视线范围内，甲醇是颗粒地幔中第二丰富的分子（相对于 H2O 为 7%）。实验室实验表明，仅用尘埃颗粒的紫外线照射很难解释隐含的丰度。颗粒表面反应或直接从气相中出来的冷凝也一定发挥作用，但各种过程的相对贡献很难估计。 3.53 微米特征的光学深度将甲醇对 W33A 中 6.8 微米特征的贡献限制在 10% 或更少，需要至少一种其他化合物对此特征的贡献，而对 4.9 微米吸收带的估计贡献甚至更小。只有甲醛 (H2CO) 的一小部分贡献与观察到的 3.53 微米带轮廓一致。与甲醇相反，冰幔内的光化学反应可以很容易地产生甲醛。
A recently detected absorption feature at 3.53 microns in the spectrum of W33A has been assigned to methanol (CH3OH). Its optical depth implies that methanol is the second most abundant molecule (7 percent relative to H2O) in the grain mantles in the line of sight toward W33A observed to date. Laboratory experiments have shown that the implied abundance is difficult to explain by UV irradiation of the dust grains alone. Grain surface reactions or condensation directly out of the gas phase must also play roles, but the relative contributions of the various processes are difficult to estimate. The optical depth of the 3.53-micron feature constrains the contribution of methanol to the 6.8-micron feature in W33A to be 10 percent or less, requiring the contribution of at least one other compound to this feature, while the estimated contribution to the 4.9-micron absorption band is even smaller. Only a small contribution of formaldehyde (H2CO) is consistent with the observed 3.53-micron band profile. In contrast to methanol, formaldehyde can be produced readily by photochemical reactions within the ice mantle.