Kepler Object of Interest Network I. First results combining ground and space-based observations of Kepler systems with transit timing variations

摘要

During its four years of photometric observations, the Kepler space telescopedetected thousands of exoplanets and exoplanet candidates. One of Kepler'sgreatest heritages has been the confirmation and characterization of hundredsof multi-planet systems via Transit Timing Variations (TTVs). However, thereare many interesting candidate systems displaying TTVs on such long time scalesthat the existing Kepler observations are of insufficient length to confirm andcharacterize them by means of this technique. To continue with Kepler's uniquework we have organized the "Kepler Object of Interest Network" (KOINet). Thegoals of KOINet are, among others, to complete the TTV curves of systems whereKepler did not cover the interaction timescales well. KOINet has beenoperational since March, 2014. Here we show some promising first resultsobtained from analyzing seven primary transits of KOI-0410.01, KOI-0525.01,KOI-0760.01, and KOI-0902.01 in addition to Kepler data, acquired during thefirst and second observing seasons of KOINet. While carefully choosing thetargets we set demanding constraints about timing precision (at least 1 minute)and photometric precision (as good as 1 part per thousand) that were achievedby means of our observing strategies and data analysis techniques. ForKOI-0410.01, new transit data revealed a turn-over of its TTVs. We carried outan in-depth study of the system, that is identified in the NASA's DataValidation Report as false positive. Among others, we investigated agravitationally-bound hierarchical triple star system, and a planet-starsystem. While the simultaneous transit fitting of ground and space-based dataallowed for a planet solution, we could not fully reject the three-starscenario. New data, already scheduled in the upcoming 2018 observing season,will set tighter constraints on the nature of the system.