Detection of transit timing variations in excess of one hour in the Kepler multi-planet candidate system KOI 806 with the GTC

TL;DR

This paper reports the detection of large transit timing variations exceeding one hour in the Kepler multi-planet candidate system KOI 806, supporting its planetary nature and resonance configuration.

Contribution

First detection of significant TTVs over one hour in KOI 806, confirming resonance and planetary system characteristics using Kepler and GTC data.

Findings

Detected TTV of -103.5 minutes in KOI 806.02

No strong color dependence in transit depth observed

Large TTVs consistent with resonant, eccentric planetary orbits

Abstract

We report the detection of transit timing variations (TTVs) well in excess of one hour in the Kepler multi-planet candidate system KOI 806. This system exhibits transits consistent with three separate planets -- a Super-Earth, a Jupiter, and a Saturn -- lying very nearly in a 1:2:5 resonance, respectively. We used the Kepler public data archive and observations with the Gran Telescopio de Canarias to compile the necessary photometry. For the largest candidate planet (KOI 806.02) in this system, we detected a large transit timing variation of -103.5$\pm$6.9 minutes against previously published ephemeris. We did not obtain a strong detection of a transit color signature consistent with a planet-sized object; however, we did not detect a color difference in transit depth, either. The large TTV is consistent with theoretical predictions that exoplanets in resonance can produce large transit timing variations, particularly if the orbits are eccentric. The presence of large TTVs among the bodies in this systems indicates that KOI806 is very likely to be a planetary system. This is supported by the lack of a strong color dependence in the transit depth, which would suggest a blended eclipsing binary.