后T金牛星的一次小行星撞击可能导致的恒星金属增强
A Possible Stellar Metallic Enhancement in Post-T Tauri Stars by a Planetesimal Bombardment
摘要：
拥有行星的恒星的光球比没有行星的恒星具有更大的金属丰度。在目前的工作中，我们研究的可能性，早期的金属富集的光球的撞击星子在第一个20- 30万年。在这里，我们探索这种污染过程模拟向内迁移的行星与其轨道内部的星子盘的相互作用。结果显示了落在恒星上的星子的百分比。我们确定了行星的偏心率（$e_p$）和迁移的时间尺度（$τ$）对落入星子的速率的依赖性。对于非常快的迁移（$τ=10^2$年和$τ=10^3$年），平均运动共振中没有捕获，与$e_p$的值无关。然后，由于行星的迁移，星子遭受与行星的近距离接触，其中80%以上被驱逐出系统。对于缓慢的迁移（$τ=10^5$ yr和$τ=10^6$ yr），与行星碰撞的百分比随着行星偏心率的增加而减少。对于$e_p=0$和$e_p=0.1$，大多数的星子都是在2：1共振中被捕获的，其中超过65%的星子与恒星相撞。虽然木星质量的行星迁移到非常短的近心距离需要不切实际的高圆盘质量，但对于较小的迁移行星来说，这些要求要小得多。我们对缓慢迁移的0.1 $M_{\rm Jupiter}$行星的模拟，甚至要求一个可能的原始盘比原始太阳星云大三倍，产生最大的[Fe/H]富集度为0.18 dex。这些计算为解释热彗星系外行星的金属丰度提供了可能性。
英文摘要：
The photospheres of stars hosting planets have larger metallicity than stars lacking planets. In the present work we study the possibility of an earlier metal enrichment of the photospheres by means of impacting planetesimals during the first 20-30Myr. Here we explore this contamination process by simulating the interactions of an inward migrating planet with a disc of planetesimal interior to its orbit. The results show the percentage of planetesimals that fall on the star. We identified the dependence of the planet's eccentricity ($e_p$) and time scale of migration ($τ$) on the rate of infalling planetesimals. For very fast migrations ($τ=10^2$yr and $τ=10^3$yr) there is no capture in mean motion resonances, independently of the value of $e_p$. Then, due to the planet's migration the planetesimals suffer close approaches with the planet and more than 80% of them are ejected from the system. For slow migrations ($τ=10^5$yr and $τ=10^6$yr) the percentage of collisions with the planet decrease with the increase of the planet's eccentricity. For $e_p=0$ and $e_p=0.1$ most of the planetesimals were captured in the 2:1 resonance and more than 65% of them collided with the star. Whereas migration of a Jupiter mass planet to very short pericentric distances requires unrealistic high disc masses, these requirements are much smaller for smaller migrating planets. Our simulations for a slowly migrating 0.1 $M_{\rm Jupiter}$ planet, even demanding a possible primitive disc three times more massive than a primitive solar nebula, produces maximum [Fe/H] enrichments of the order of 0.18 dex. These calculations open possibilities to explain hot Jupiters exoplanets metallicities.
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