MODELING THE ROSSITER–MCLAUGHLIN EFFECT: IMPACT OF THE CONVECTIVE CENTER-TO-LIMB VARIATIONS IN THE STELLAR PHOTOSPHERE
MODELING THE ROSSITER–MCLAUGHLIN EFFECT: IMPACT OF THE CONVECTIVE CENTER-TO-LIMB VARIATIONS IN THE STELLAR PHOTOSPHERE
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DOI：
10.3847/0004-637x/819/1/67
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发表时间：
2016-01
期刊：
影响因子：
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通讯作者：
H. Cegla;M. Oshagh;M. Oshagh;Christopher A. Watson;P. Figueira;Nuno C. Santos;Sergiy Shelyag
中科院分区：
文献类型：
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作者：
H. Cegla;M. Oshagh;M. Oshagh;Christopher A. Watson;P. Figueira;Nuno C. Santos;Sergiy Shelyag
对Rossiter-McLaughlin(RM)效应的观测提供了恒星-行星排列的信息，这可以为行星迁移和演化理论提供信息。在这里，我们超越了经典的RM模型，并探索了在恒星盘和非高斯恒星光球层轮廓上变化的对流蓝移的影响。基于太阳表面对流的辐射三维磁流体力学模拟，我们模拟了一颗围绕类太阳恒星运行四天的排列的热木星，并注入了中心到边缘速度(和轮廓形状)的变化。我们的模型和经典的RM模型之间的残差依赖于固有轮廓宽度和v sin i；残差的幅度随着v sin i的增加和固有轮廓宽度的减小而增加。对于慢自转的恒星，残差主要是中心到肢体的对流变化(振幅在10 S cm S−1到∼1 m S−1之间)；而对于较快自转的恒星，主要的残留特征是非高斯内蕴廓线(振幅在0.5到9 m S−1之间)。当影响因子为0时，忽略对流中心到肢体的变化会导致∼倾角在10°-20°之间不确定，即使真实的v sin i是已知的。此外，忽略对非对称本征轮廓的适当建模对较快速自转的恒星(例如，vSin i=6 KM S−1)有更大的影响，并在测量的倾角中造成∼20°量级的系统误差。因此，忽视恒星表面对流的影响可能会使恒星-行星排列测量产生偏差，从而影响行星迁移和演化的理论。
Observations of the Rossiter–McLaughlin (RM) effect provide information on star–planet alignments, which can inform planetary migration and evolution theories. Here, we go beyond the classical RM modeling and explore the impact of a convective blueshift that varies across the stellar disk and non-Gaussian stellar photospheric profiles. We simulated an aligned hot Jupiter with a four-day orbit about a Sun-like star and injected center-to-limb velocity (and profile shape) variations based on radiative 3D magnetohydrodynamic simulations of solar surface convection. The residuals between our modeling and classical RM modeling were dependent on the intrinsic profile width and v sin i; the amplitude of the residuals increased with increasing v sin i and with decreasing intrinsic profile width. For slowly rotating stars the center-to-limb convective variation dominated the residuals (with amplitudes of 10 s of cm s−1 to ∼1 m s−1); however, for faster rotating stars the dominant residual signature was due a non-Gaussian intrinsic profile (with amplitudes from 0.5 to 9 m s−1). When the impact factor was 0, neglecting to account for the convective center-to-limb variation led to an uncertainty in the obliquity of ∼10°–20°, even though the true v sin i was known. Additionally, neglecting to properly model an asymmetric intrinsic profile had a greater impact for more rapidly rotating stars (e.g., v sin i = 6 km s−1) and caused systematic errors on the order of ∼20° in the measured obliquities. Hence, neglecting the impact of stellar surface convection may bias star–planet alignment measurements and consequently theories on planetary migration and evolution.