2517463

Target RA (J2000): 349.215973 and deg Target Dec (J2000): 5.69600 and deg Gaia GMag: 9.88 Programme ID: CH_PR140068 Programme Manager: EGGER PI of observing programme: Benz Title of programme: Axis 1 - Constraining the abundance of water in hot planets (HotWatermelon) Abstract: Planets located close enough to their star experience evaporation which leads to a dichotomy in the possible gas content of these objects. These planets either contain more than around one percent of gas (in mass) or no gas at all (see Owen and Wu 2017). This dichotomy when expressed in term of mass-radius relation implies the existence of a region in the mass-radius diagram of hot planets where dry planets cannot exist. We propose to observe planets that could lie in this region with CHEOPS. Combining a precise radius and mass will allow us to identify planets in this forbidden region hence showing that they have to contain volatiles most likely water. Our data combined with future JWST observations will also constrain the efficiency of evaporation. [truncated! Please see actual data for full text]

目标赤经（J2000坐标系）：349.215973 度；目标赤纬（J2000坐标系）：5.69600 度；盖亚G星等（Gaia GMag）：9.88；项目编号：CH_PR140068；项目主管：埃格（EGGER）；观测项目首席研究员：本茨（Benz）；项目标题：轴1——约束热行星中的水丰度（HotWatermelon）
摘要：与宿主恒星距离足够近的系外行星会发生蒸发作用，该过程会导致此类天体的气体含量呈现二分特性：这类行星要么拥有质量占比约1%以上的气体，要么完全不含任何气体（详见Owen与Wu 2017年的研究成果）。若以质量-半径关系来表述这一二分特性，则意味着在热行星的质量-半径分布图中存在一个"禁区"，干燥行星无法在该区域内存在。我们提议利用CHEOPS对可能处于该区域的行星开展观测。通过结合高精度的半径与质量测量数据，我们能够识别出处于该禁区内的行星，从而证实这些行星必然含有极有可能为水的挥发性物质。本数据集结合未来詹姆斯·韦布空间望远镜（JWST）的观测数据，还可用于约束行星蒸发的作用效率。
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