Prospects for Refining Kepler TTV Masses using TESS Observations

TL;DR

This study assesses how TESS observations can enhance Kepler TTV-based planetary mass and eccentricity measurements, despite lower signal-to-noise ratios, predicting significant improvements for a subset of systems.

Contribution

It introduces the use of KL divergence to quantify improvements in TTV constraints when combining Kepler and TESS data, providing forecasts for future observational gains.

Findings

TESS data can significantly improve mass constraints for 6-14 planets during the nominal mission.

Extended TESS missions could enhance this to 12-25 planets.

Lower SNR in TESS data poses challenges but still allows meaningful improvements.

Abstract

In this paper we investigate systems previously identified to exhibit transit timing variations (TTVs) in Kepler data, with the goal of predicting the expected improvements to the mass and eccentricity constraints that will arise from combining Kepler data with future data from the TESS mission. We advocate for the use of the Kullback-Leibler (KL) divergence as a means to quantify improvements in the measured constraints. Compared to the original Kepler data, the TESS data will have a lower signal-to-noise ratio, rendering some of the planetary transits undetectable, and lowering the accuracy with which the transit mid-time can be estimated. Despite these difficulties, out of the 55 systems (containing 143 planets) investigated, we predict that the collection of short-cadence data by TESS will be of significant value (i.e. it will improve the mass uncertainty such that the KL divergence is > 0.1) for approximately 6 - 14 planets during the nominal mission, with the range primarily driven by the uncertain precision with which transit mid-times will be recovered from TESS data. In an extended mission this would increase to a total of approximately 12 - 25 planets.