Maintaining the Ephemeris of 20 CoRoT Planets: Transit Minimum Times and Potential Transit Timing Variations

TL;DR

This study updates the orbital timings of 20 CoRoT planets using ground-based observations, identifying potential transit timing variations and correcting ephemeris inconsistencies from earlier data.

Contribution

It provides new transit minimum times for 20 CoRoT planets and investigates transit timing variations and ephemeris accuracy with ground-based follow-up.

Findings

Detection of significant transit timing variations in CoRoT 3b, 11b, 13b, 27b.

Identification of ephemeris inconsistencies in CoRoT 18b and 20b.

Most observed transit times have negative O-C values within expected uncertainties.

Abstract

We present 33 transit minimum times of 20 transiting planets discovered by the CoRoT mission, which have been obtained from ground-based observations since the mission's end in 2012, with the objective to maintain the ephemeris of these planets. Twelve of the observed planets are in the CoRoT fields near the galactic center and the remaining eight planets are in the fields near the anticenter. We detect indications for significant transit timing variations in the cases of CoRoT 3b, 11b, 13b, 27b. For two more planets (CoRoT 18b and 20b) we conclude that timing offsets in early follow-up observations led to ephemeris in discovery publications that are inconsistent with timings from follow-up observations in later epochs. In the case of CoRoT-20b, this might be due to the influence from a further non-transiting planet. We also note that a significant majority (23 of 33) of our reported minimum times have negative O-C values, albeit most of them are within the expected uncertainty of the ephemeris.