Roxanne Ligi


AstroFIt 2 – COFUND fellow since June 1, 2017

Project ended May 31, 2020

INAF Research Centre: Osservatorio Astronomico di Brera

Email: roxanne.ligi at

Curriculum vitae

Publications list


Project title: INTASTE – Combining interferometry and asteroseismology: a new insight on exoplanet characterization


After the discovery of thousands of exoplanets, the new challenge of the 21th has become their characterization. Exoplanet parameters are strongly linked to stellar parameters, in particular because the two main techniques used to detect exoplanets provide the ratio of planetary and stellar masses (radial velocity measurements) and radii (transit method). Thus, the determination of the parameters of the stellar hosts are indissociable from exoplanet characterization.

The aim of the project is to investigate how the combination of two powerful methods, interferometry and asteroseismology, can provide very accurate stellar parameters of stars hosting exoplanets. Interferometry is one of the most accurate method to obtain direct estimates of the stellar diameter, which, combined with the distance, give a model-independent measure of the radius. In turn, asteroseismology is the best tool for determining the age of stars and also supply accurate global stellar parameters. Together, interferometry and asteroseimology are the optimal method to provide accurate estimates of stellar masses.

We will use the best instruments to date to perform interferometric (VEGA and PAVO on CHARA) and asteroseismic (HARPS-N/ESO, SOPHIE/OHP, then ESPRESSO) observations of a selection of targets. The data will be reduced thanks to the strong skills of the applicant in interferometry and those developed at Brera Observatory in asteroseismology. They will provide a test for the expected accuracy on ages (~10%), masses (~3%) and radii (~2%). We will then be able to estimate the exoplanets parameters with the best precision ever reached. This will allow to derive their internal composition, giving new insights on their formation.

This project is a key to optimize the scientific return of PLATO, TESS and CHEOPS space missions which goal is the detection and characterization of transiting exoplanets around bright stars. The achievement of these missions strongly depends on the ability of the stellar community to provide reliable stellar parameters.