A Holistic and Probabilistic Approach to the Ground-based Data of HAT-P-19 System

TL;DR

This study provides an updated, comprehensive analysis of the HAT-P-19 system by integrating diverse observational data and modeling techniques to refine its physical and orbital characteristics, and explores potential causes of transit timing variations.

Contribution

It introduces a holistic probabilistic approach combining ground-based and archival data for detailed characterization of the HAT-P-19 exoplanet system, including transit timing analysis.

Findings

No periodic transit timing variations detected.

Stellar activity likely causes transit timing residuals.

Planet has a bloated atmosphere with a small core.

Abstract

We update the fundamental physical and orbital properties of the transiting hot-Saturn type exoplanet HAT-P-19b and its host star HAT-P-19 as a result of the global modeling of our high-precision transit light curves, an archive spectrum, radial velocity observations, brightness values from broadband photometry in different passbands, and the precise distance of the system derived from its Gaia parallax. We collected all the light curves obtained with ground-based photometry by amateur and professional observers, measured mid-transit times, analyzed their differences from calculated transit timings based on reference ephemeris information, which we update as a result. We haven't found any periodicity in the residuals of a linear trend, which we attribute to the accumulation of uncertainties in the reference mid-transit time and the orbital period. We discuss the potential origins of the variation in transit timings briefly and find stellar activity as the most likely cause. Finally, we comment on the scenarios describing the formation and migration of this hot-Saturn type exoplanet with a bloated atmosphere yet a small core, although it is orbiting a metal-rich ([Fe / H] = 0.24 dex) host star based on the planetary, orbital, and stellar parameters of the system that we derived from our global model, the age and the evolutionary history of the star.