Evidence for the Late Arrival of Hot Jupiters in Systems with High Host-star Obliquities
Evidence for the Late Arrival of Hot Jupiters in Systems with High Host-star Obliquities
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DOI：
10.3847/1538-3881/ac69ef
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发表时间：
2022-04
期刊：
影响因子：
--
通讯作者：
J. Hamer;K. Schlaufman
中科院分区：
文献类型：
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作者：
J. Hamer;K. Schlaufman
已经证明，具有大质量热恒星主恒星的热木星系统表现出大范围的恒星倾角。另一方面，具有低质量、冷原星的热木星系统的恒星倾角通常接近于零。热木星和存在于低质量主序恒星中的对流包层之间有效的潮汐相互作用是对这些观测结果的一种流行解释。如果这个解释是准确的，那么对准的系统应该比不对准的系统更古老。同样，热木星主星的对流包层质量应该是其倾角的有效预测指标。我们通过高质量的天空投影倾角推断得出热木星主星的均匀恒星参数，包括对流包层质量。使用薄盘恒星群的银河系速度色散作为相对年龄代理，我们发现倾角大于中位数的热木星宿主恒星比倾角小于中位数的热木星宿主恒星更老。对于对流包络质量分数小于中位数的热木星主星，两者的相对年龄差异较大，在3.6σ水平上显著。我们确定恒星质量，而不是对流包层质量，是热木星系统中恒星倾角的最佳预测因子。对这些观测结果最好的解释是，许多在不对准系统中的热木星在它们的原行星盘消散很久之后才到达它们的宿主恒星附近。观测到的年龄偏移与对流包层质量的关系表明，潮汐重新调整有助于形成有对流包层的热木星。
It has been shown that hot Jupiters systems with massive, hot stellar primaries exhibit a wide range of stellar obliquities. On the other hand, hot Jupiter systems with low-mass, cool primaries often have stellar obliquities close to zero. Efficient tidal interactions between hot Jupiters and the convective envelopes present in lower-mass main-sequence stars have been a popular explanation for these observations. If this explanation is accurate, then aligned systems should be older than misaligned systems. Likewise, the convective envelope mass of a hot Jupiter’s host star should be an effective predictor of its obliquity. We derive homogeneous stellar parameters—including convective envelope masses—for hot Jupiter host stars with high-quality sky-projected obliquity inferences. Using a thin-disk stellar population’s Galactic velocity dispersion as a relative age proxy, we find that hot Jupiter host stars with larger-than-median obliquities are older than hot Jupiter host stars with smaller-than-median obliquities. The relative age difference between the two populations is larger for hot Jupiter host stars with smaller-than-median fractional convective envelope masses and is significant at the 3.6σ level. We identify stellar mass, not convective envelope mass, as the best predictor of stellar obliquity in hot Jupiter systems. The best explanation for these observations is that many hot Jupiters in misaligned systems arrived in the close proximity of their host stars long after their parent protoplanetary disks dissipated. The dependence of observed age offset on convective envelope mass suggests that tidal realignment contributes to the population of aligned hot Jupiters orbiting stars with convective envelopes.