标题： HD 169142原行星盘中的气体：赫歇尔的视角 显示英文标题

标题： Gas in the protoplanetary disc of HD 169142: Herschel's view

摘要： 为了同时研究围绕年轻Herbig Ae型恒星HD 169142的盘中的气体和尘埃成分，我们利用赫歇尔空间天文台上的PACS仪器获得了远红外观测数据。 这项工作属于开放时间关键项目GASPS，该项目旨在研究原行星盘的演化。 为了限制外部盘的气体属性，我们在几个关键气体谱线上观测了该恒星，包括[OI] 63.2和145.5微米，[CII] 157.7微米，CO 72.8和90.2微米，以及o-H2O 78.7和179.5微米。 我们在光谱中仅检测到[OI] 63.2微米线，并为其他谱线推导出上限值。 我们用PACS测光和亚毫米阵列获得的12/13CO数据补充了我们的数据集。 此外，我们从光学光谱和UV到mm波段的测光数据中推导出准确的恒星参数。 我们使用三维辐射传输代码MCFOST对尘埃连续谱进行建模，并将此模型作为输入，使用热化学代码ProDiMo分析气体谱线。 我们的数据集与一个简单模型一致，在这个模型中，气体和尘埃在一个从20到200AU之间具有连续结构的盘中混合良好，但这不是一个唯一解。 我们的建模努力使我们能够通过同时拟合几种起源于不同区域的物种的谱线来限制盘中的气固质量比以及PAHs的相对丰度。 我们的结果与气体贫乏且有大紫外过量的盘不一致；在这个盘中仍然存在5.0+/−2.0倍10^(-3)Msun的气体质量，这与早期的CO观测结果一致。 显示英文摘要

摘要： In an effort to simultaneously study the gas and dust components of the disc surrounding the young Herbig Ae star HD 169142, we present far-IR observations obtained with the PACS instrument onboard the Herschel Space Observatory. This work is part of the Open Time Key Project GASPS, which is aimed at studying the evolution of protoplanetary discs. To constrain the gas properties in the outer disc, we observed the star at several key gas-lines, including [OI] 63.2 and 145.5 micron, [CII] 157.7 micron, CO 72.8 and 90.2 micron, and o-H2O 78.7 and 179.5 micron. We only detect the [OI] 63.2 micron line in our spectra, and derive upper limits for the other lines. We complement our data set with PACS photometry and 12/13CO data obtained with the Submillimeter Array. Furthermore, we derive accurate stellar parameters from optical spectra and UV to mm photometry. We model the dust continuum with the 3D radiative transfer code MCFOST and use this model as an input to analyse the gas lines with the thermo-chemical code ProDiMo. Our dataset is consistent with a simple model in which the gas and dust are well-mixed in a disc with a continuous structure between 20 and 200 AU, but this is not a unique solution. Our modelling effort allows us to constrain the gas-to-dust mass ratio as well as the relative abundance of the PAHs in the disc by simultaneously fitting the lines of several species that originate in different regions. Our results are inconsistent with a gas-poor disc with a large UV excess; a gas mass of 5.0 +/- 2.0 times 10^(-3) Msun is still present in this disc, in agreement with earlier CO observations.