Exoplanet demographic surveys have revealed that close-in (${\lesssim}$1 au) small planets orbiting stars in the Milky Way's thick disk are ${\sim}50\%$ less abundant than those orbiting stars in the Galactic thin disk. One key difference between the two stellar populations is the time at which they emerged: thick disk stars are the likely product of cosmic noon (redshift $z {\sim}2$), an era characterized by high star formation rate, massive and dense molecular clouds, and strong supersonic turbulence. Solving for the background radiation field in these early star-forming regions, we demonstrate that protoplanetary disks at cosmic noon experienced radiation fields up to ${\sim}7$ orders of magnitude more intense than in solar neighborhood conditions. Coupling the radiation field to a one-dimensional protoplanetary disk evolution model, we find that external UV photoevaporation destroys protoplanetary disks in just ${\sim}$0.2--0.5 Myr, limiting the timescale over which planets can assemble. Disk temperatures exceed the sublimation temperatures of common volatile species for ${\gtrsim}$Myr timescales, predicting more spatial homogeneity in gas chemical composition. Our calculations imply that the deficit in planet occurrence around thick disk stars should be even more pronounced for giant planets, particularly those at wide orbital separations, predicting a higher rocky-to-giant planet ratio in the Galactic thick disk vs.~thin disk.
Exploring the Sun's birth radius and the distribution of planet building blocks in the Milky Way galaxy: A multi-zone Galactic chemical evolution approach
Giant Planets and Eccentric Orbits Are Common Around Galactic Thick Disc Stars
Yale University（耶鲁大学）；The Observatories of the Carnegie Institution for Science（卡内基科学研究所天文台）；Universidad de Concepción（康塞普西翁大学）；Gemini Observatory（吉米尼天文台）；NSF’s NOIRLab（美国国家光学红外天文实验室）；Pomona College（波莫纳学院）
A chemo-dynamical search for planet-candidate hosts of possible extragalactic origin
CAS Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台光学天文重点实验室）；School of Science, Hangzhou Dianzi University（杭州电子科技大学理学院）；Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University（北京师范大学天文与前沿科学研究院）；School of Physics and Astronomy, Beijing Normal University（北京师范大学物理与天文学院）
Searching for Exoplanets Born Outside the Milky Way: VOYAGERS Survey Design
University of Wisconsin-Madison（威斯康星大学麦迪逊分校）；Massachusetts Institute of Technology（麻省理工学院）；Penn State University（宾夕法尼亚州立大学）；University of California Santa Cruz（加州大学圣克鲁兹分校）；University of Cambridge（剑桥大学）；University of Geneva（日内瓦大学）；University of Warwick（华威大学）；University of Florida（佛罗里达大学）；Space Telescope Science Institute（太空望远镜科学研究所）；University of Birmingham（伯明翰大学）；University of Southern Queensland（昆士兰南部大学）；University of Edinburgh（爱丁堡大学）；University of Amsterdam（阿姆斯特丹大学）
The TESS-Keck Survey II: An Ultra-Short Period Rocky Planet and its Siblings Transiting the Galactic Thick-Disk Star TOI-561
我们报告了TOI-561的发现，这是一个位于银河系厚盘中的多行星系统，其中包含一颗岩石，超短周期行星（USP）。这颗明亮的恒星（$V=10.2$）拥有三颗小型凌日行星：TOI-561 b（TOI-561.02，P=0.44天，$R_b = 1.45\pm0.11\,R_\oplus$），c（TOI-561.01，P=10.8天，$R_c=2.90\pm0.13\,R_\oplus$）和d（TOI-561.03，P=16.3天，$R_d=2.32\pm0.16\,R_\oplus$）。这颗恒星的化学成分（[Fe/H] $=-0.41\pm0.05$，[ $α$ /H] $=+0.23\pm0.05$）和运动学上与银河系厚盘一致，使TOI-561成为迄今发现的最古老（$10\pm3\,$ Gyr）和最贫金属的行星系统之一。我们动态地确认行星b和c的径向速度从W。M.凯克天文台高分辨率中阶梯光谱仪。行星b的质量和密度为$3.2\pm0.8\,M_\oplus$和$5.5^{+2.0}_{-1.6}\,$ g $\,$ cm $^{-3}$，与岩石组成一致。它的密度低于平均值，与贫铁的组成相一致，尽管不排除类似地球的铁与硅酸盐的比例。行星c是$7.0\pm2.3\,M_\oplus$和$1.6\pm0.6\,$ g $\,$ cm $^{-3}$，与覆盖着低质量挥发性包层的内部岩石核心一致…
Modelling the Milky Way's exoplanet population based on cosmological galaxy simulations
Universitat de Barcelona (UB)（巴塞罗那大学）；Reial Acadèmia de Ciències i Arts de Barcelona（巴塞罗那皇家科学与艺术学院）；Shanghai Jiao Tong University（上海交通大学）；Observatori Fabra（法布拉天文台）；Observatório Nacional, MCTI（巴西国家天文台）
Towards a global model for planet formation in layered MHD wind-driven discs: A population synthesis approach to investigate the impact of low viscosity and accretion layer thickness
Center for Space and Habitability, University of Bern（伯尔尼大学太空与宜居性中心）；Division of Space Research and Planetary Sciences, Physics Institute, University of Bern（伯尔尼大学物理研究所空间研究与行星科学系）
Chemical connections between low-mass stars and planets building blocks investigated by stellar population synthesis
在一个单一的模型中连接恒星和行星的属性并不简单。恒星星族综合模型是探索恒星和行星观测组合统计约束的关键。贝桑松恒星星族合成模型（Robin et al. 2003，Lagarde et al. 2017）现在包括使用恒星演化代码STAREVOL（Lagarde et al. 2012，Amard et al. 2016）计算的恒星演化轨迹。它提供了54种化学物种的全局（M，R，Teff等）和恒星的化学性质。它可以研究银河系的不同星系群（晕，凸起，薄和厚盘）和特定的观测调查。在这里，我们将贝桑松模型与简单的化学计量模型（Santos et al. 2017）结合起来，以确定行星构建块（PBB）的预期组成。我们研究了银河系不同恒星星族中多溴联苯预期化学丰度的趋势和相关性（Cabral等人，2018年）。
