Close-in planets are in jeopardy, as their host stars evolve off the main sequence (MS) to the subgiant and red giant phases. In this paper, we explore the influences of the stellar mass (in the range 1.5-2 M ☉), mass-loss prescription, planet mass (from Neptune up to 10 Jupiter masses), and eccentricity on the orbital evolution of planets as their parent stars evolve to become subgiants and red giants. We find that planet engulfment along the red giant branch is not very sensitive to the stellar mass or mass-loss rates adopted in the calculations, but quite sensitive to the planetary mass. The range of initial separations for planet engulfment increases with decreasing mass-loss rates or stellar masses and increasing planetary masses. Regarding the planet's orbital eccentricity, we find that as the star evolves into the red giant phase, stellar tides start to dominate over planetary tides. As a consequence, a transient population of moderately eccentric close-in Jovian planets is created that otherwise would have been expected to be absent from MS stars. We find that very eccentric and distant planets do not experience much eccentricity decay, and that planet engulfment is primarily determined by the pericenter distance and the maximum stellar radius.
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机译：近距离行星处于危险之中，因为它们的宿主恒星从主序列（MS）演化到亚巨相和红色巨相。在本文中，我们探索了恒星质量（在1.5-2 M range范围内），质量损失处方，行星质量（从海王星到10个木星质量）以及偏心距对行星轨道演化的影响。父母的恒星演化成亚族和红色巨人。我们发现，沿着红色巨型分支的行星吞没对计算中采用的恒星质量或质量损失率不是很敏感，但是对行星质量却非常敏感。随着质量损失率或恒星质量的降低以及行星质量的增加，行星吞没的初始分离范围增加。关于行星的轨道偏心率，我们发现随着恒星演化成红色巨相，恒星潮汐开始主导行星潮汐。结果，产生了一个短暂的适度偏心的近端Jovian行星，而MS恒星原本不会出现这些瞬变。我们发现，非常偏心和遥远的行星不会经历太多的偏心率衰减，并且行星的吞噬主要由近心距和最大恒星半径决定。
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