COMPLEX MOLECULES TOWARD LOW-MASS PROTOSTARS: THE SERPENS CORE
COMPLEX MOLECULES TOWARD LOW-MASS PROTOSTARS: THE SERPENS CORE
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DOI：
10.1088/0004-637x/740/1/14
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发表时间：
2011-10-10
影响因子：
4.9
通讯作者：
van Dishoeck, Ewine F.
中科院分区：
文献类型：
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作者：
Oeberg, Karin I.;van der Marel, Nienke;van Dishoeck, Ewine F.
在高质量的原恒星热核中，通常会探测到气相的复杂有机分子。对低质量原恒星和外流的探测相对罕见，更大的样本是研究化学如何对其环境做出反应的关键。在预测的指导下，复杂的有机分子的形式在CH 3OH丰富的冰和热或非热蒸发与CH 3OH，我们已经确定了三个视线在巨蛇座核心SMM 1，SMM 4，SMM 4-W-这可能是丰富的复杂的有机物。使用IRAM 30 m望远镜，CH_3CHO和CH_3OCH_3的窄谱线（FWHM为1-2 km s（-1））被检测到朝向所有源，HCOOCH_3朝向SMM_1和SMM_4-W，而C_2H_5OH根本没有。当应用CH 3OH旋转温度时，单个复杂有机物的束平均丰度相对于CH 3OH在0.6%至10%之间。复杂有机物丰度的总和也有一个数量级的变化，最明亮的原恒星SMM 1的化学成分最丰富。丰度范围与其他低质量源的束平均观测结果相比很好。复杂的有机丰度是相同的数量级对低质量的原恒星和高质量的热核心，但HCOOCH 3是相对更重要的对低质量的原恒星。这是一致的顺序冰光化学，占主导地位的CHO含产品在低温和早期。
Gas-phase complex organic molecules are commonly detected toward high-mass protostellar hot cores. Detections toward low-mass protostars and outflows are comparatively rare, and a larger sample is the key to investigate how the chemistry responds to its environment. Guided by the prediction that complex organic molecules form in CH3OH-rich ices and thermally or non-thermally evaporate with CH3OH, we have identified three sight lines in the Serpens core-SMM1, SMM4, and SMM4-W-which are likely to be rich in complex organics. Using the IRAM 30 m telescope, narrow lines (FWHM of 1-2 km s(-1)) of CH3CHO and CH3OCH3 are detected toward all sources, HCOOCH3 toward SMM1 and SMM4-W, and C2H5OH not at all. Beam-averaged abundances of individual complex organics range between 0.6% and 10% with respect to CH3OH when the CH3OH rotational temperature is applied. The summed complex organic abundances also vary by an order of magnitude, with the richest chemistry toward the most luminous protostar SMM1. The range of abundances compare well with other beam-averaged observations of low-mass sources. Complex organic abundances are of the same order of magnitude toward low-mass protostars and high-mass hot cores, but HCOOCH3 is relatively more important toward low-mass protostars. This is consistent with a sequential ice photochemistry, dominated by CHO-containing products at low temperatures and early times.