Tight constraints on the existence of additional planets around HD 189733

TL;DR

This study used transit timing observations of HD 189733 to place stringent upper mass limits on potential additional planets, finding no evidence for planets above Earth mass near key orbital resonances.

Contribution

The paper provides the strongest constraints to date on additional planets in the HD 189733 system using transit timing analysis.

Findings

No planets above 1 Earth mass near 1:2 and 2:1 resonances.

No planets above 2.2 Earth masses near 3:5 and 5:3 resonances.

Transit timing residuals show no evidence of additional planets.

Abstract

We report a transit timing study of the transiting exoplanetary system HD 189733. In total we observed ten transits in 2006 and 2008 with the 2.6-m Nordic Optical Telescope, and two transits in 2007 with the 4.2-m William Herschel Telescope. We used Markov-Chain Monte Carlo simulations to derive the system parameters and their uncertainties, and our results are in a good agreement with previously published values. We performed two independent analyses of transit timing residuals to place upper mass limits on putative perturbing planets. The results show no evidence for the presence of planets down to 1 Earth mass near the 1:2 and 2:1 resonance orbits, and planets down to 2.2 Earth masses near the 3:5 and 5:3 resonance orbits with HD 189733b. These are the strongest limits to date on the presence of other planets in this system.