TATOO: a tidal-chronology standalone tool to estimate the age of massive close-in planetary systems

Abstract

The presence of a massive close-in planet with an orbital period of a few days or less around a low-mass star can possibly results in a strong variation of the properties of the central star. Indeed, star-planet tidal interactions generate exchanges of angular momentum that can results in tidal spin-up. This effect could then lead to gyrochronological ages biased towards younger ages. Aims. This article provides the community with TATOO, a standalone tool based on tidal-chronology, to estimate the age of a massive close-in planetary system by only using its observed properties: mass of the planet and the star, stellar rotational and planetary orbital periods. I used the numerical code described in Gallet et al. (2018) to create a large multi-parametric grid of synthetic star-planet systems evolution, and 3D interpolation method to provide a fairly precise age estimate, using tidal-chronology technique, of any given planetary systems composed of at least of one massive close-in planet. About half of the planetary systems investigated in this work are subject to tidal spin-up bias. I pointed out that this bias linearly scales with the ratio between rotation to orbital period, making this quantity a useful proxy to rapidly investigate the need to use tidal-chronology. Moreover, while being model dependent, TATOO can also be used even if no rotational departure is present. In that case, it gives results in agreement with the classical gyrochronological analysis. TATOO is a useful tool specifically designed for massive close-in planetary systems that can also be used as a classical gyrochronological tool. For now it is the only publicly available software to estimate the age of massive close-in planetary systems subject to tidal spin-up. In that sense, tidal-chronology can be seen as a first order correction of the impact of tidal interaction on gyrochronology.