标题： DM Tau原行星盘中冷态水蒸气丰度的灵敏限制 显示英文标题

标题： Sensitive limits on the abundance of cold water vapor in the DM Tau protoplanetary disk

摘要： 我们利用赫歇尔空间天文台的HIFI仪器对DM Tau原行星盘中的正交和亚平行水蒸气基态发射线进行了灵敏探测。在1_{10}--1_{01}线（4.2毫开尔文的0.5公里/秒通道）和1_{11}--0_{00}线（12.6毫开尔文）中，在3σ水平下未检测到强线。然而，我们在宽频带光谱仪中报告了对1_{10}--1_{01}线非常初步的检测，其强度为T_{mb}= 2.7毫开尔文，宽度为5.6公里/秒，积分强度为16.0毫开尔文·公里/秒。后者构成了一个6σ的检测。无论这一初步检测是否真实存在，模型计算表明，我们对线强度的灵敏限制排除了盘面紫外线照射区域中水的有效解吸。我们假设超过95%-99%的水冰被锁定在聚集的颗粒中，这些颗粒已经沉降到盘面中间层。 显示英文摘要

摘要： We performed a sensitive search for the ground-state emission lines of ortho- and para-water vapor in the DM Tau protoplanetary disk using the Herschel/HIFI instrument. No strong lines are detected down to 3sigma levels in 0.5 km/s channels of 4.2 mK for the 1_{10}--1_{01} line and 12.6 mK for the 1_{11}--0_{00} line. We report a very tentative detection, however, of the 1_{10}--1_{01} line in the Wide Band Spectrometer, with a strength of T_{mb}=2.7 mK, a width of 5.6 km/s and an integrated intensity of 16.0 mK km/s. The latter constitutes a 6sigma detection. Regardless of the reality of this tentative detection, model calculations indicate that our sensitive limits on the line strengths preclude efficient desorption of water in the UV illuminated regions of the disk. We hypothesize that more than 95-99% of the water ice is locked up in coagulated grains that have settled to the midplane.