THOT · Comprehensive code for stellar dating, and analysis of exoplanetary systems observed by direct imaging

Comprehensive code for stellar dating, and analysis of exoplanetary systems observed by direct imaging

Knowledge of how stars are born, evolve and die underpins much of our understanding of the Universe. In this effort, stellar dating is critical. It helps to interpret observational data and to understand the underlying physics of very different astrophysical issues. Although there are a number of techniques in the literature for estimating stellar ages, none is suitable for all-stars, and the uncertainties are very large in general. As a consequence, there are no research groups in the world dating stars using all the techniques available. What we find is that a number of research groups dating stars using a subset of these techniques, for which they are specialized. Therefore, there is a lack of a general tool for automated stellar dating. It is critical and timely to develop this tool as current and future space missions such as Kepler/K2 and TESS (NASA), Gaia and Plato (ESA), JWST (NASA-ESA-CSA), etc., will provide a large amount of very accurate observational data. Gaia will observe 1 billion stars, for example. The automated analysis of these data will be a must, and stellar dating is far from being automated nowadays. The overarching aims of THOT are: 1) to gather all the techniques available for stellar dating, updating those having huge potential for application to data from new and upcoming missions (gyrochronology, isochrones, asteroseismology, and kinematics), and 2) to develop software to automate this dating with a double purpose: a) to offer a user-friendly code for stellar dating, and b) to evaluate the age of exoplanetary systems observed by direct imaging. It is the first time, up to our knowledge, that such a global project for stellar dating has been tackled. Stellar-mass (M) and radius (R) are key variables for estimating stellar ages. Unfortunately, they cannot be directly observed for most of the stars. In these cases, one of the most used options is to estimate these quantities as a function of other observables (such as effective temperature, metallicity, luminosity, etc.) thanks to data-driven relations. For facing the first objective of THOT, we must include a goal 0: update the empirical relations for estimating stellar masses and radii using observational data coming from eclipsing binaries and asteroseismology. During this MSCA we have combined an exceptional database and machine learning techniques for providing, for the first time in some of the stellar characterization fields, an important step beyond the state-of-the-art in empirical estimations of stellar masses, radii, and ages, this last using chemical clocks and gyrochronology. We have reached a stellar-mass estimation with an uncertainty of around 5%, a radius estimation with an uncertainty of around 3%, and age estimations with an error of the order of 1 Gyr for isolated stars. This last value is beyond our expectations. Finally, we have gathered the most recent results and codes for stellar dating using stellar activity, isochrones Bayesian fitting, and asteroseismology.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз