在存在恒星变率的情况下重建行星transit信号的迭代滤波器
An iterative filter to reconstruct planetary transit signals in the presence of stellar variability
摘要：
广泛用于减少恒星变化对天基凌日调查影响的去趋势算法不适合于估计已确认行星的参数，因为它们会不可避免地改变凌日信号。我们提出了一种检测后去趋势算法，该算法在保留过境信号的同时滤除过境期间以外的其他时间尺度上的信号。我们比较这种新的过滤器的性能，一个完善的预检测去趋势算法，通过应用到一组20个模拟光变曲线包含行星凌日，恒星的变化，和仪器噪声预期的CoRoT空间任务，并进行分析适合的过境。与探测前基准相比，新的探测后滤波器在行星与恒星半径比、系统尺度和碰撞参量方面系统地产生了显著减少的误差（相对误差的中位数减少约40%）。这对于活跃的恒星尤其重要，因为由变化引起的误差可能会主导行星参数的最终误差预算。除了改进行星参数估计外，新的滤波器还保留了行星轨道周期的所有信号，因此也可以用于搜索行星反射的光。
英文摘要：
The detrending algorithms which are widely used to reduce the impact of stellar variability on space-based transit surveys are ill-suited for estimating the parameters of confirmed planets, as they unavoidably alter the transit signal. We present a post-detection detrending algorithm, which filters out signal on other timescales than the period of the transit while preserving the transit signal. We compare the performance of this new filter to a well-established pre-detection detrending algorithm, by applying both to a set of 20 simulated light curves containing planetary transits, stellar variability, and instrumental noise as expected for the CoRoT space mission, and performing analytic fits to the transits. Compared to the pre-detection benchmark, the new post-detection filter systematically yields significantly reduced errors (median reduction in relative error over our sample of about 40%) on the planet-to-star radius ratio, system scale and impact parameter. This is particularly important for active stars, where errors induced by variability can otherwise dominate the final error budget on the planet parameters. Aside from improving planet parameter estimates, the new filter preserves all signal at the orbital period of the planet, and thus could also be used to search for light reflected by the planet.
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