Line-profile tomography of exoplanet transits I: The Doppler shadow of HD 189733b
Line-profile tomography of exoplanet transits I: The Doppler shadow of HD 189733b
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系外行星凌日的线剖面断层扫描 I：HD 189733b 的多普勒阴影
DOI：
10.1111/j.1365-2966.2009.16131.x
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
D. Queloz
中科院分区：
文献类型：
--
作者：
A. Cameron;V. Bruce;G. Miller;A. Triaud;D. Queloz
我们提出了一种直接的方法来分离行星凌日时被其主恒星遮挡的星光成分，并将其应用于明亮的凌日行星HD 189733b的光谱。我们将恒星互相关函数的全局形状建模为一个边缘变暗的旋转轮廓和一个代表平均光球线轮廓的多普勒核心的高斯曲线的卷积。凌日期间被行星阻挡的光是具有相同本征宽度的高斯光，其穿过线轮廓的轨迹产生了对不对准角的精确测量和v sin I的独立测量。我们表明，即使v sin I小于本征线轮廓的宽度，行星投射的旅行多普勒“阴影”也会在线轮廓中产生可识别的扭曲，这是可以直接建模的。对缺失星光轨迹的直接测量可以得到预测的恒星旋转速率、平均局部光球线轮廓的固有宽度、预测的自旋轨道失调角和系统的质心速度。结合光度旋转周期，结果给出了恒星半径的几何测量，如果在恒星光球中存在少量的微分旋转，则该测量结果与高精度凌日光度测量结果非常吻合。
We present a direct method for isolating the component of the starlight blocked by a planet as it transits its host star, and apply it to spectra of the bright transiting planet HD 189733b. We model the global shape of the stellar cross-correlation function as the convolution of a limb-darkened rotation profile and a gaussian representing the Doppler core of the average photospheric line profile. The light blocked by the planet during the transit is a gaussian of the same intrinsic width, whose trajectory across the line profile yields a precise measure of the misalignment angle and an independent measure of v sin I. We show that even when v sin I is less than the width of the intrinsic line profile, the travelling Doppler "shadow" cast by the planet creates an identifiable distortion in the line profiles which is amenable to direct modelling. Direct measurement of the trajectory of the missing starlight yields self-consistent measures of the projected stellar rotation rate, the intrinsic width of the mean local photospheric line profile, the projected spin-orbit misalignment angle, and the system's centre-of-mass velocity. Combined with the photometric rotation period, the results give a geometrical measure of the stellar radius which agrees closely with values obtained from high-precision transit photometry if a small amount of differential rotation is present in the stellar photosphere.
DOI：
10.1088/0004-637x/709/1/159
发表时间：
2009-08
期刊：
The Astrophysical Journal
影响因子：
--
作者：
D. Anderson;C. Hellier;M. Gillon;M. Gillon;A. Triaud;B. Smalley;L. Hebb;A. Cameron;P. Maxted;D. Queloz;R. West;S. Bentley;B. Enoch;K. Horne;T. Lister;M. Mayor;N. Parley;F. Pepe;D. Pollacco;D. Ségransan;S. Udry;D. Wilson;D. Wilson
通讯作者：
D. Anderson;C. Hellier;M. Gillon;M. Gillon;A. Triaud;B. Smalley;L. Hebb;A. Cameron;P. Maxted;D. Queloz;R. West;S. Bentley;B. Enoch;K. Horne;T. Lister;M. Mayor;N. Parley;F. Pepe;D. Pollacco;D. Ségransan;S. Udry;D. Wilson;D. Wilson