Ariel (Atmospheric Remote-sensing Infrared Exoplanet Large-survey) is a mission of the European Space Agency (ESA). When a planet passes in front of its star, a little of the starlight filters through the planet's atmosphere, and the gases there leave a fingerprint in it. Ariel will measure that fingerprint for about 1,000 planets, to learn what their atmospheres are made of and how warm they are.
ESA selected Ariel as a medium-class mission in March 2018 and adopted it in November 2020. Its telescope has an elliptical main mirror of 1.1 by 0.7 metres, and its spectrometer works in the infrared. It is planned to launch in 2029 on an Ariane 6 rocket and to settle in an orbit around the Sun-Earth Lagrange point 2, about 1.5 million kilometres from Earth, for a nominal four years of observing. The mission is still under development.
An atmosphere measurement is only as good as the knowledge of the star behind it. The size of a planet comes from how much starlight it blocks, so it depends on the star's size, and the star's age and mass say what kind of system the planet belongs to. Stars whose brightness oscillates (asteroseismology, the study of starquakes) give the most direct measurements of both.
Where I come in
I have been a member of the Ariel Science Consortium since 2021, in the Stellar Characterisation working group, in the sub-group that works on stellar age, mass and radius. My MSc dissertation at the University of Porto, defended in 2022, determined the ages and masses of oscillating stars in the Ariel input catalogue, and I implemented a routine that computes the small frequency separation for the grid of the stellar characterisation code PARAM.
I also contributed to Magrini et al. (2022), the first paper of the working group's series, which derives homogeneous stellar parameters for 187 planet-host stars on the Ariel target list. My part was the Bayesian stellar characterisation runs with PARAM for a subset of the sample. In 2022 I presented this work in Portuguese at DFA Week in Porto, as a talk at the national physics conference FÍSICA 2022, and as a poster at the national astronomy meeting ENAA XXXII in Lisbon.