Title: Gas and dust in the Beta Pictoris Moving Group as seen by the Herschel Space Observatory Show Chinese title

Title: 猎户座β运动集团中的气体和尘埃，如赫歇尔空间望远镜所见

Abstract: Context. Debris discs are thought to be formed through the collisional grinding of planetesimals, and can be considered as the outcome of planet formation. Understanding the properties of gas and dust in debris discs can help us to comprehend the architecture of extrasolar planetary systems. Herschel Space Observatory far-infrared (IR) photometry and spectroscopy have provided a valuable dataset for the study of debris discs gas and dust composition. This paper is part of a series of papers devoted to the study of Herschel PACS observations of young stellar associations. Aims. This work aims at studying the properties of discs in the Beta Pictoris Moving Group (BPMG) through far-IR PACS observations of dust and gas. Methods. We obtained Herschel-PACS far-IR photometric observations at 70, 100 and 160 microns of 19 BPMG members, together with spectroscopic observations of four of them. Spectroscopic observations were centred at 63.18 microns and 157 microns, aiming to detect [OI] and [CII] emission. We incorporated the new far-IR observations in the SED of BPMG members and fitted modified blackbody models to better characterise the dust content. Results. We have detected far-IR excess emission toward nine BPMG members, including the first detection of an IR excess toward HD 29391.The star HD 172555, shows [OI] emission, while HD 181296, shows [CII] emission, expanding the short list of debris discs with a gas detection. No debris disc in BPMG is detected in both [OI] and [CII]. The discs show dust temperatures in the range 55 to 264 K, with low dust masses (6.6*10^{-5} MEarth to 0.2 MEarth) and radii from blackbody models in the range 3 to 82 AU. All the objects with a gas detection are early spectral type stars with a hot dust component. Show Chinese abstract

Abstract: 上下文。 碎片盘被认为是由星子的碰撞研磨形成的，可以看作是行星形成的结果。 了解碎片盘中气体和尘埃的特性有助于我们理解系外行星系统的结构。 赫歇尔空间天文台远红外（IR）测光和光谱数据为研究碎片盘气体和尘埃成分提供了有价值的数据集。 本文是系列论文的一部分，致力于研究赫歇尔PACS对年轻恒星集团的观测。 目标。 本工作旨在通过远红外PACS观测尘埃和气体来研究毕宿星团（BPMG）中的盘特性。 方法。 我们获得了19个BPMG成员在70、100和160微米处的赫歇尔-PACS远红外测光观测数据，以及其中四个成员的光谱观测数据。 光谱观测集中在63.18微米和157微米处，旨在检测[OI]和[CII]发射。 我们将新的远红外观测数据纳入BPMG成员的SED中，并拟合修改后的黑体模型以更好地表征尘埃含量。 结果。 我们已经检测到九个BPMG成员的远红外过量辐射，包括对HD 29391的首次红外过量检测。恒星HD 172555显示出[OI]发射，而HD 181296显示出[CII]发射，扩大了具有气体检测的碎片盘的短名单。 BPMG中没有一个碎片盘同时检测到[OI]和[CII]。 这些盘的尘埃温度范围为55至264 K，尘埃质量较低（6.6*10^{-5}MEarth至0.2 MEarth），并从黑体模型中得到的半径范围为3至82 AU。 所有具有气体检测的天体都是早期光谱类型恒星，并具有热尘埃成分。