Seminars at FGG
Chemically Connecting Compositionally Diverse Stars to their Planetary Interiors
Speaker: Yoshi Eschen (University of Warwick (United Kingdom))
Date and time: 2026-08-27 11:00
Planets and stars form from the same proto-stellar material. Hence the stellar refractory elemental abundances are assumed to be strongly linked to rocky planet interiors. This is also found for the refractory elemental abundances of the Sun and Earth. For exoplanets, this compositional link has been recently suggested and explored in small demographic studies. However, the sample of rocky planets around metal-poor stars is limited. This makes it challenging to find and validate potentially vital chemical trends. We present a novel machine learning approach to identify planet hosting stars of interest to fill in the lack of well-characterised small planets around metal-poor stars. We present newly characterised systems containing Ultra-Short Period Super-Earths and Sub-Neptunes around compositionally-diverse stars. These planetary systems were observed with photometry and radial velocity allowing us to measure their radius and masses precisely. We modelled their interior structures for which we further developed tools to link stellar abundances to the core and mantle mass fractions of the planet. These give insights into the elemental abundance ratios of the planets. Hence, we directly study the connection between the planet and host star abundances. These new discoveries significantly add to the sample of rocky planets around thick disk stars and will be followed by further detections and characterisations from our machine learning algorithm.