Context: Several recent studies have found that planet migration in adiabatic discs differs significantly from migration in isothermal discs. Depending on the thermodynamic conditions, i.e., the effectiveness of radiative cooling, and the radial surface density profile, planets migrate inward or outward. Clearly, this will influence the semimajor axis - mass distribution of planets as predicted by population synthesis simulations. Aims: Our goal is to study the global effects of radiative cooling, viscous torque desaturation and gap opening as well as stellar irradiation on the tidal migration of a synthetic planet population. Methods: We combine results from several analytical studies and 3D hydrodynamic simulations in a new semi-analytical migration model for the application in our planet population synthesis calculations. Results: We find a good agreement of our model with torques obtained in a 3D radiative hydrodynamic simulations. We find three convergence zones in a typical disc, towards which planets migrate from the in- and outside, affecting strongly the migration behavior of low-mass planets. Interestingly, this leads to slow type II like migration behavior for low-mass planets captured in those zones even without an ad hoc migration rate reduction factor or a yet to be defined halting mechanism. This means that the new prescription of migration including non-isothermal effects makes the preciously widely used artificial migration rate reduction factor obsolete. Conclusions: Outward migration in parts of a disc makes some planets survive long enough to become massive. The convergence zones lead to a potentially observable accumulations of low-mass planets at certain semimajor axes. Our results indicate that further studies of the mass where the corotation torque saturates will be needed since its value has a major impact on the properties of planet populations.
Migration and Growth of Protoplanetary Embryos II: Emergence of Proto-Gas-Giants Cores versus Super Earths' Progenitor
几乎$15-20%$的太阳型恒星包含一个或多个气体巨行星。根据地核吸积的设想，在获得它们的气体包层之前，必须形成质量是地球质量十倍或更大的超临界地核。将气态巨行星的形成概率与其出生盘中气体和固体的供应联系起来是很自然的。然而，更多的超级地球人口表明：1）行星的构建材料并不短缺，2）气体巨星的生长障碍可能与它们是否可以合并成超临界核心有关，3）超级地球可能是失败的核心，在严重耗尽之前没有达到足够的质量来启动有效的气体吸积。在这里，我们构建了一个模型的基础上的假设，原行星胚胎广泛迁移之前，他们组装成真正的行星。我们构造了一个厄米-胚胎代码的基础上统一的粘性照射盘模型和处方的胚胎盘潮汐相互作用。该代码用于模拟1）胚胎的会聚迁移，以及2）它们的近距离接触和凝结。在太阳型恒星的祖先周围，气体巨行星的祖先超临界质量核心主要形成于具有相对较高（$\gtrsim 10^{-7} M_\odot$ yr $^{-1}$）质量吸积率的原恒星盘中，而超级地球系统（失败的核心）更有可能出现在具有适度质量吸积率的出生盘中，这是由于平均运动共振势垒和保留效率。
Hydrodynamical simulations of protoplanetary disks including irradiation of stellar photons. I. Resolution study for Vertical Shear Instability (VSI)
近年来，流体动力学（HD）模型已成为描述原行星盘中气体运动学的重要模型，特别是与光蒸发和/或磁驱动风模型相结合。我们专注于诊断垂直范围的VSI在203细胞每刻度高度和暗示在什么分辨率每刻度高度，我们获得收敛。最后，我们确定的区域，EUV，FUV和X射线是占主导地位的磁盘。我们使用PLUTO代码进行全球HD模拟。我们采用了一个全球等温吸积盘装置，2.5维（2维，3个组件），其中包括一个径向域从0.5到5.0和一个近似完整的径向扩展。我们将每个刻度高度50个单元确定为解决VSI的下限。对于更高的分辨率，大于50个细胞每刻度高度，我们观察到的动能的饱和水平的收敛。我们还能够识别“主体”模式的增长，具有更高的增长率以获得更高的分辨率。在70个局部轨道之后达到完全能量饱和和湍流稳定状态。我们确定的EUV加热区域的位置定义的径向柱密度为10 $^{19}$ cm $^{-2}$位于$H_\mathrm{R}\sim9.7$，和FUV/X射线加热的边界层定义的10 $^{22}$ cm $^{-2}$位于$H_\mathrm{R}\sim6.2$，有必要引入热大气的需要。我们首次报道了在r-Z平面上大尺度垂直速度运动的特征层之间存在小尺度涡旋。这样的涡流可能导致粉尘集中，促进晶粒生长。我们的研究结果突出了重要性，结合光蒸发过程在未来的高分辨率研究的湍流和吸积过程中的磁盘。
The Impact of Irradiation on the Radius and Thermal Evolution of Transiting Brown Dwarfs
School of Earth and Space Exploration, Arizona State University（亚利桑那州立大学地球与空间探索学院）；Department of Astronomy and Astrophysics, University of California, Santa Cruz（加州大学圣克鲁兹分校天文学与天体物理系）；Institute for Astronomy, University of Hawai‘i（夏威夷大学天文研究所）；William H. Miller III Department of Physics & Astronomy, Johns Hopkins University（约翰斯·霍普金斯大学威廉·H·米勒三世物理与天文学系）
The discovery of WASP-151b, WASP-153b, WASP-156b: Insights on giant planet migration and the upper boundary of the Neptunian desert
To investigate the origin of the features discovered in the exoplanet population, the knowledge of exoplanets' mass and radius with a good precision is essential. In this paper, we report the discovery of three transiting exoplanets by the SuperWASP survey and the SOPHIE spectrograph with mass and radius determined with a precision better than 15 %. WASP-151b and WASP-153b are two hot Saturns with masses, radii, densities and equilibrium temperatures of 0.31^{+0.04}_{-0.03} MJ, 1.13^{+0.03}_{-0.03} RJ, 0.22^{-0.03}_{-0.02} rhoJ and 1, 290^{+20}_{-10} K, and 0.39^{+0.02}_{-0.02} MJ, 1.55^{+0.10…
Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. I. Confirmation of an Eccentric, Cool Jupiter With an Interior Earth-sized Planet Orbiting Kepler-1514
尽管发现系外行星的凌日方法严重偏向于短轨道周期，但已知轨道周期大于100天的凌日系外行星的样本不多。长期的径向速度（RV）调查是确认这些信号的关键，并为从其宿主恒星接受中等至低辐射的行星产生一组行星质量和密度。在这里，我们进行RV观测开普勒-1514从凯克我望远镜使用高分辨率中阶梯光谱仪。从这些数据中，我们测量了统计学验证的巨型（$1.108\pm0.023$ $R_{\rm J}$）系外行星开普勒1514 b的质量，其轨道周期为218天，为$5.28\pm0.22$ $M_{\rm J}$。这颗冷（$\sim$ 390 K）巨行星的体积密度为$4.82^{+0.26}_{-0.25}$ g cm $^{-3}$，与由电子简并压力支撑的核心一致。我们还从RV和凌日观测中推断出$0.401^{+0.013}_{-0.014}$的轨道偏心率，这与行星-行星散射和盘腔迁移模型是一致的。开普勒-1514系统包含一个地球大小的开普勒感兴趣的物体，轨道为10.5天，我们在统计上验证了假阳性的情况，包括那些涉及邻近恒星的情况。主恒星的亮度（$V$ =11.8）和开普勒-1514 b的长周期、低辐射和高密度相结合，使该系统成为一组罕见的已知系外行星系统之一，也是一个可以继续研究的系统。
Vertical shear instability in two-moment radiation-hydrodynamical simulations of irradiated protoplanetary disks II. Secondary instabilities and stability regions
