Transit timing variations in WASP-10b induced by stellar activity
Transit timing variations in WASP-10b induced by stellar activity
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DOI：
10.1093/mnras/stt111
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发表时间：
2013-01
影响因子：
4.8
通讯作者：
S. Barros;G. Boué;G. Boué;G. Boué;N. P. Gibson;D. Pollacco;A. Santerne;F. Keenan;I. Skillen;R. Street
中科院分区：
文献类型：
--
作者：
S. Barros;G. Boué;G. Boué;G. Boué;N. P. Gibson;D. Pollacco;A. Santerne;F. Keenan;I. Skillen;R. Street
据Maciejewski等人报道，热木星WASP-10b显示出类似于3.5分钟振幅的凌日时间变化（TTVs）。这些作者提出，观测到的ttv是由一个0.1 M-Jup的扰动伴星引起的，其轨道周期类似于5.23 d，因此接近于WASP-10b外层的5.3平均运动共振。为了验证这一假设，我们展示了用福克斯北望远镜和利物浦望远镜获得的WASP-10b的8个新的过境光曲线。新的光曲线，连同之前发表的22条光曲线，都是用马尔科夫链蒙特卡罗传输拟合代码建模的。据报道，WASP-10b的凌日深度差异被认为是由于恒星黑子引起的主星亮度调制。假设恒星在活动最小时更亮，我们倾向于行星半径较小。我们发现R-p = 1.039(-0.049)(+0.043)R（Jup）与Johnson et al.和Maciejewski et al.一致。最近的研究没有发现该系统存在显著偏心的证据。我们提出了一个圆形轨道的一致系统参数，并改进了WASP-10b的轨道星历。我们的齐次推导的凌日时间不支持先前声称的TTV信号，它强烈依赖于先前发布的两次被错误标准化的凌日。然而，线性星历表在统计上并不适合WASP-10b的凌日时间。我们认为观测到的凌日时间变化是由于掩星特征或系统。我们讨论并举例说明了掩星点特征对测量过境时间的影响，并表明尽管在过境光曲线中难以区分出口和入口的点掩星，但它们对测量过境时间有显著影响。我们的结论是，如果我们考虑到斑点的特征，WASP-10b的凌日时间与线性星历一致，除了一次凌日（历元143）是部分凌日。因此，目前还没有证据表明WASP-10b的伴星存在。我们的结果支持在开普勒样本中缺乏热木星的ttv。
The hot-Jupiter WASP-10b was reported by Maciejewski et al. to show transit timing variations (TTVs) with an amplitude of similar to 3.5 min. These authors proposed that the observed TTVs were caused by a 0.1 M-Jup perturbing companion with an orbital period of similar to 5.23 d, and hence, close to the outer 5: 3 mean-motion resonance with WASP-10b. To test this scenario, we present eight new transit light curves of WASP-10b obtained with the Faulkes Telescope North and the Liverpool Telescope. The new light curves, together with 22 previously published ones, were modelled with a Markov Chain Monte Carlo transit fitting code. Transit depth differences reported for WASP-10b are thought to be due to starspot-induced brightness modulation of the host star. Assuming the star is brighter at the activity minimum, we favour a small planetary radius. We find R-p = 1.039(-0.049)(+0.043)R(Jup) in agreement with Johnson et al. and Maciejewski et al. Recent studies find no evidence for a significant eccentricity in this system. We present consistent system parameters for a circular orbit and refine the orbital ephemeris of WASP-10b. Our homogeneously derived transit times do not support the previous claimed TTV signal, which was strongly dependent on two previously published transits that have been incorrectly normalized. Nevertheless, a linear ephemeris is not a statistically good fit to the transit times of WASP-10b. We show that the observed transit time variations are due to spot occultation features or systematics. We discuss and exemplify the effects of occultation spot features in the measured transit times and show that despite spot occultation during egress and ingress being difficult to distinguish in the transit light curves, they have a significant effect in the measured transit times. We conclude that if we account for spot features, the transit times of WASP-10b are consistent with a linear ephemeris with the exception of one transit (epoch 143) which is a partial transit. Therefore, there is currently no evidence for the existence of a companion to WASP-10b. Our results support the lack of TTVs of hot-Jupiters reported for the Kepler sample.