AI 中文总结
该研究利用MESA代码构建127颗宿主恒星的内部模型，发现行星形成的金属丰度阈值约为0.007，揭示了恒星Z₀与年龄、Zₛ的关系，以及行星半径的影响因素。
AI 中文摘要
我们收集了127颗宿主恒星（外加6颗候选体）的数据，并将其作为约束条件，使用MESA代码构建这些宿主恒星的内部模型。从这些模型中得出两个重要结论：第一，除少数恒星外，宿主恒星的金属丰度（Z₀）大于0.007，这表明当Z₀≈0.007时，行星的形成可能受到抑制；第二，关于银盘的化学演化，对于给定的Z₀值，考虑最古老的恒星，Z₀与年龄（t₉）之间存在线性关系，该线在Z₀=0时约为t₉=13.4 Gyr，与银河系的年龄一致，这种线性关系持续到t₉≈6 Gyr，且在t₉=2-6 Gyr之间，Z₀的最大值保持恒定。我们进一步对文献中归类为红团簇（RC）恒星的12颗宿主恒星进行了建模，明确考虑了红巨星分支上的质量损失，这些模型凸显了质量损失假设在确定RC宿主恒星的初始质量和年龄方面的关键作用，及其对近距行星的存活和演化的影响。本研究的另一项关键成果是发现了宿主恒星的Z₀与观测到的金属丰度（Zₛ）之间的关系，我们得到了模型输入参数Z₀作为恒星质量、半径和Zₛ的函数的实用表达式，该表达式可用于估算因微观扩散导致的表面金属丰度降低后的Z₀。我们还推导了行星质量相对于轨道半长轴和宿主恒星质量的表达式，该表达式可能指示这些行星形成的内盘区域的质量分布（热木星除外），行星半径似乎取决于行星质量、辐照能量以及轨道周期。
英文摘要
We compiled data for 127 hosts (plus six candidates) and used them as constraints to construct interior models of the hosts using the {\small MESA} code. Two significant conclusions emerge from these models. First, except for a few stars, the hosts' metallicity ($Z_0$) is greater than 0.007. This suggests a possible suppression of the occurrence of planets below $Z_0\approx0.007$. Second, it concerns how chemical evolution unfolds in the galactic disc. For a given $Z_0$ value, considering the oldest stars, there is a linear relationship between $Z_0$ and age ($t_9$). This line is around $t_9=13.4$ Gyr at $Z_0=0$, a value consistent with the age of the Galaxy. The linear relationship continues until around $t_9=6$ Gyr, and the maximum value of $Z_0$ remains constant between $t_9=2-6$ Gyr. We further modelled 12 hosts classified as red clump (RC) stars in the literature, explicitly accounting for mass loss along the red giant branch. These models highlight the critical role of mass-loss assumptions in determining the initial masses and ages of RC hosts, and their implications for the survival and evolution of close-in planets. Another key outcome of this study is the discovery of the relationship between $Z_0$ and the observed metallicity ($Z_{\rm s}$) for the hosts. We obtain a useful expression for $Z_0$, the input parameter for the models, as a function of stellar mass, radius, and $Z_{\rm s}$. This expression can be used to estimate $Z_0$ based on the reduced surface metallicity due to microscopic diffusion. We also derive an expression for planetary mass relative to the orbital semimajor axis and host mass. This expression may indicate a mass distribution near the inner disc where these planets formed, except for hot-Jupiters. Planet radii appear to depend on the planet's mass and irradiation energy, as well as the orbital period.
Comments29 pages, 13 figures
