Exoplanet Ephemerides Change Observations (ExoEcho). II. Transit timing variation analysis of Brown Dwarfs around Solar-type Stars

TL;DR

This study uses TESS data to analyze long-term transit timing variations of brown dwarf companions around solar-type stars, aiming to detect orbital decay and understand tidal interactions, but finds no significant decay evidence yet.

Contribution

It is the first to perform a TTV analysis on transiting brown dwarfs around solar-type stars, constraining tidal interactions and proposing future observation strategies.

Findings

No significant orbital decay detected in current data.

Identified promising targets for future TTV observations.

Simulations suggest specific stars as optimal for detecting decay.

Abstract

Transit timing variation (TTV) is a useful tool for studying the orbital properties of transiting objects. However, few TTV studies have been done on transiting brown dwarfs (BDs) around solar-type stars. Here we study the long-term TTV of a population of close BD companions around solar-type stars using TESS data. We use the measured orbital period change rate to constrain the tidal interaction strength between the host star and the BD companion and put limits on the destruction timescale of these transiting BDs. However, we find no statistically significant evidence of orbital decay or expansion in our sample based on the current data. This may be due to either poor observational data or inherently weak tidal dissipation. We then perform simulations to investigate future observation strategies for detecting orbital decay of transiting BDs, which show NGTS-7A b, TOI-263~b and LP 261-75 b are the most promising targets in the next few years. Our study demonstrates the potential of TTV technique to probe the formation and evolution of close BD companions around solar-type stars.