论文标题
双星中的星球吞噬签名
Planet Engulfment Signatures in Twin Stars
论文作者
论文摘要
可以通过增强岩石行星材料增强后吞噬恒星的光球中的耐火元素来推断行星吞噬。这种难治性富集受到出色的内部混合过程，即由对流膜和辐射芯之间的平均分子量反向分子重量梯度引起的热盐混合。使用MESA恒星模型，我们量化了行星吞噬后吞噬签名的强度和持续时间。我们发现，热盐混合在第一个$ \ sim $ 5 $ - $ 45 MYR后造成的统一后，削弱了签名$ \ sim $ 2 $ 2 $ 2，然后通过重力通过较长的时间标准而枯竭。 0.5-1.2 $ m _ {\ odot} $质量范围的太阳金属星星在$ \ sim $ 1 Myr $ -8 Gyr中具有可观察的签名时间标准，具体取决于吞噬星的质量和吞噬的材料量。早期类型的恒星表现出较大的初始耐火性增强功能，但耗尽更快。 Solar-like stars ($M$ = 0.9$-$1.1 $M_{\odot}$) maintain observable signatures ($>$0.05 dex) over timescales of $\sim$20 Myr$-$1.7 Gyr for nominal 10 $M_{\oplus}$ engulfment events, with longer-lived signatures occurring for low-metallicity and/or hotter stars (1 $ m _ {\ odot} $，$ \ sim $ 2 $ - $ 3 GYR）。由于氦的重力沉降抑制了热盐混合，因此在零时代的主序列后出现较大的信号（1 $ m _ {\ odot} $，$ \ sim $ 1.5 gyr），吞噬事件产生了较大的信号。这些结果表明，可能很难观察到几个Gyr旧的太阳能恒星中的吞噬特征。
Planet engulfment can be inferred from enhancement of refractory elements in the photosphere of the engulfing star following accretion of rocky planetary material. Such refractory enrichments are subject to stellar interior mixing processes, namely thermohaline mixing induced by an inverse mean-molecular-weight gradient between the convective envelope and radiative core. Using MESA stellar models, we quantified the strength and duration of engulfment signatures following planet engulfment. We found that thermohaline mixing dominates during the first $\sim$5$-$45 Myr post-engulfment, weakening signatures by a factor of $\sim$2 before giving way to depletion via gravitational settling on longer timescales. Solar metallicity stars in the 0.5-1.2 $M_{\odot}$ mass range have observable signature timescales of $\sim$1 Myr$-$8 Gyr, depending on the engulfing star mass and amount of material engulfed. Early type stars exhibit larger initial refractory enhancements but more rapid depletion. Solar-like stars ($M$ = 0.9$-$1.1 $M_{\odot}$) maintain observable signatures ($>$0.05 dex) over timescales of $\sim$20 Myr$-$1.7 Gyr for nominal 10 $M_{\oplus}$ engulfment events, with longer-lived signatures occurring for low-metallicity and/or hotter stars (1 $M_{\odot}$, $\sim$2$-$3 Gyr). Engulfment events occurring well after the zero-age main sequence produce larger signals due to suppression of thermohaline mixing by gravitational settling of helium (1 $M_{\odot}$, $\sim$1.5 Gyr). These results indicate that it may be difficult to observe engulfment signatures in solar-like stars that are several Gyr old.
