M型矮星周围存在水世界族群的确凿证据仍难以获得
Conclusive evidence for a population of water-worlds around M-dwarfs remains elusive
AI总结：
本文通过含岩石核与H/He大气的热演化模型，证明亚海王星与1:1硅酸盐-冰水世界的质量-半径关系简并，仅凭质量和半径无法确认M型矮星周围水世界族群。
摘要：
小质量、近轨道系外行星族群被分为超级地球和亚海王星两类。我们计算了具有物理依据的亚海王星质量-半径关系，这些行星拥有岩石核心和以H/He为主的大气层，并考虑了其热演化、辐照和质量损失。对于质量小于约10 M⊕的行星，我们发现亚海王星保留的大气质量比例随行星质量而缩放，并表明由此得到的质量-半径关系与由硅酸盐-冰组成比例为1:1的“水世界”结果存在简并。我们进一步证明，推导得到的质量-半径关系与观测到的围绕M型矮星运行的系外行星族群高度吻合，而且仅凭行星质量和半径不足以确定某些亚海王星的组成。最后，我们强调当前系外行星统计数据显示，超级地球与亚海王星的数量比例随恒星质量（因而也随光度）和年龄增加而上升，这两者都指示了热驱动的大气逃逸过程。因此，在质量-半径图中进行组成推断时，不应忽视这些过程。
英文摘要：
The population of small, close-in exoplanets is bifurcated into super-Earths and sub-Neptunes. We calculate physically motivated mass-radius relations for sub-Neptunes, with rocky cores and H/He dominated atmospheres, accounting for their thermal evolution, irradiation and mass-loss. For planets $\lesssim 10~$M$_\oplus$, we find that sub-Neptunes retain atmospheric mass fractions that scale with planet mass and show that the resulting mass-radius relations are degenerate with results for `water-worlds' consisting of a 1:1 silicate-to-ice composition ratio. We further demonstrate that our derived mass-radius relation is in excellent agreement with the observed exoplanet population orbiting M-dwarfs and that planet mass and radii alone are insufficient to determine the composition of some sub-Neptunes. Finally, we highlight that current exoplanet demographics show an increase in the ratio of super-Earths to sub-Neptunes with both stellar mass (and therefore luminosity) and age, which are both indicative of thermally driven atmospheric escape processes. Therefore, such processes should not be ignored when making compositional inferences in the mass-radius diagram.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
