论文标题
行星吞噬后的长期锂丰度特征
Long-Term Lithium Abundance Signatures following Planetary Engulfment
论文作者
论文摘要
行星吞噬事件可能发生在主恒星在主序列上时。在吞噬过程中增加岩石行星材料将导致宿主星光球的难治性丰度增强，但是富集及其持续时间的水平将取决于在恒星内部发生的混合过程，例如对流，扩散和热氨基氨基氨基盐混合。我们通过建模光球锂丰度的演变来检查吞噬信号。由于锂可以在吞噬事件发生之前或之后燃烧，因此它会产生随时间和宿主星类型而变化的独特签名。使用MESA恒星模型，我们量化了这些签名的强度和持续时间，因为太阳能金属宿主星星的1、10或100 $ M _ {\ oplus} $具有散装地球组成的Planetary Companion，其大众群体为0.5 $ - $ 1.4 $ -1.4 $ m _ $ _ _ _ {\ odot} $。我们发现，锂在低质量的宿主星（$ \ lyssim 0.7 \，m_ \ odot $）上很快耗尽了几百Myrs的时间，但大量的锂富集特征可以持续Gyrs gyrs gyrs gyrs gyrs gyrs gyrs gype type Stars（$ \ sim \ sim \ sim \！0.9 \！0.9 \！0.9 \，m \，m _ _ _ _ {\ odot}。对于更大的恒星（1.3 $ - $ 1.4 $ m _ {\ odot} $），吞噬可以增强内部混合和扩散过程，从而可能减少表面锂丰度。我们预测来自系外行星吞噬的签名与观察到的富含锂的太阳能恒星以及化学不均匀二进制恒星中的丰度增强一致。
Planetary engulfment events can occur while host stars are on the main sequence. The addition of rocky planetary material during engulfment will lead to refractory abundance enhancements in the host star photosphere, but the level of enrichment and its duration will depend on mixing processes that occur within the stellar interior, such as convection, diffusion, and thermohaline mixing. We examine engulfment signatures by modeling the evolution of photospheric lithium abundances. Because lithium can be burned before or after the engulfment event, it produces unique signatures that vary with time and host star type. Using MESA stellar models, we quantify the strength and duration of these signatures following the engulfment of a 1, 10, or 100 $M_{\oplus}$ planetary companion with bulk Earth composition, for solar-metallicity host stars with masses ranging from 0.5$-$1.4 $M_{\odot}$. We find that lithium is quickly depleted via burning in low-mass host stars ($\lesssim 0.7 \, M_\odot$) on a time scale of a few hundred Myrs, but significant lithium enrichment signatures can last for Gyrs in G-type stars ($\sim \! 0.9 \, M_{\odot}$). For more massive stars (1.3$-$1.4 $M_{\odot}$), engulfment can enhance internal mixing and diffusion processes, potentially decreasing the surface lithium abundance. Our predicted signatures from exoplanet engulfment are consistent with observed lithium-rich solar-type stars and abundance enhancements in chemically inhomogeneous binary stars.
