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

• Published in: Astronomy and astrophysics (Berlin) 2020-09, Vol.641, p.A38
• Main Author: Gallet, F.
• Format: Article
• Language: English
• Subjects: Age; Angular momentum; Astrophysics; Bias; Chronology; Interpolation; Low mass stars; Orbits; Physics; Planetary evolution; Planetary rotation; Planetary systems; Stellar evolution; Stellar rotation
• ISSN: 0004-6361; 1432-0746; 1432-0756
• DOI: 10.1051/0004-6361/202038058

Context. 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 result in a strong variation in the properties of the central star. Indeed, star-planet tidal interactions generate exchanges of angular momentum that can result 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, with which to estimate the age of a massive close-in planetary system using only its observed properties: mass of the planet and the star, stellar rotation, and planetary orbital periods. Methods. I used a star-planet tidal evolution numerical code to create a large multi-parametric grid of the evolution of synthetic star-planet systems. Furthermore, using the tidal-chronology technique, I employed a 3D interpolation method to provide a fairly precise age estimate of any given planetary system composed of one massive close-in planet. Results. 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 and orbital period, making this quantity a useful proxy to rapidly investigate whether tidal-chronology needs to be used. 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. Conclusions. 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.