Schmitt Joseph R, Jenkins Jon M, Fischer Debra A
Department of Astronomy, Yale University, New Haven, CT 06511 USA.
NASA Ames Research Center, Moffett Field, CA 94035, USA.
Astron J. 2017 Apr;153(No 4). doi: 10.3847/1538-3881/aa62ad. Epub 2017 Mar 28.
The vast majority of the 4700 confirmed planets and planet candidates discovered by the space telescope were first found by the pipeline. In the pipeline, after a transit signal is found, all data points associated with those transits are removed, creating a "Swiss cheese"-like light curve full of holes, which is then used for subsequent transit searches. These holes could render an additional planet undetectable (or "lost"). We examine a sample of 114 stars with 3+ confirmed planets to see the effect that this "Swiss cheesing" may have. A simulation determined that the probability that a transiting planet is lost due to the transit masking is low, but non-neglible, reaching a plateau at ~3.3% lost in the period range of = 400 - 500 days. We then model the transits in all quarters of each star and subtract out the transit signals, restoring the in-transit data points, and use the Kepler pipeline to search the transit-subtracted (i.e., transit-cleaned) light curves. However, the pipeline did not discover any credible new transit signals. This demonstrates the validity and robustness of the pipeline's choice to use transit masking over transit subtraction. However, a follow-up visual search through all the transit-subtracted data, which allows for easier visual identification of new transits, revealed the existence of a new, Neptune-sized exoplanet. Kepler-150 f ( = 637.2 days, = 3.86 R) is confirmed using a combination of false positive probability analysis, transit duration analysis, and the planet multiplicity argument.
这架太空望远镜发现的4700颗已确认行星和行星候选体中的绝大多数最初都是由该管道系统发现的。在该管道系统中，一旦发现凌星信号，所有与这些凌星相关的数据点都会被移除，从而创建出一条布满空洞的“瑞士奶酪”般的光变曲线，然后将其用于后续的凌星搜索。这些空洞可能会使额外的行星无法被探测到（或“丢失”）。我们研究了一个包含114颗拥有3颗及以上已确认行星的恒星样本，以查看这种“瑞士奶酪化”可能产生的影响。一项模拟确定，由于凌星掩蔽导致凌星行星丢失的概率较低，但并非可以忽略不计，在周期范围为400 - 500天内，丢失率达到约3.3%的平稳状态。然后，我们对每颗恒星所有季度的凌星进行建模，并减去凌星信号，恢复凌星期间的数据点，并使用开普勒管道系统搜索减去凌星后的（即清除凌星后的）光变曲线。然而，该管道系统并未发现任何可信的新凌星信号。这证明了管道系统选择使用凌星掩蔽而非凌星减法的有效性和稳健性。然而，通过对所有减去凌星后的数据进行后续目视搜索，这使得更容易目视识别新的凌星，结果发现了一颗新的海王星大小的系外行星。通过结合误报概率分析、凌星持续时间分析和行星多重性论证，确认了开普勒 - 150 f（周期 = 637.2天，半径 = 3.86 R）。
