Insights on Research projects
Our understanding of the universe from exoplanets characterization to galactic archaeology strongly relies on our understanding of stellar dynamics. It was recently discovered that stellar evolution models that take into account the rotation of the star and associated hydrodynamic transport processes predict a much faster rotation rate than what is observed. Since then, it has been of paramount importance to understand how angular momentum is redistributed inside stars, as it could strongly modify our theory of stellar evolution, and thus the estimation of ages in the universe. In large part, this turnaround was made possible by Asteroseismology, which then became one of the leading methods for the characterization of stars. This recent branch of stellar physics consists of the analysis of oscillations of stars induced by stationary waves. It is the analog of seismology on Earth since it allows us to probe the internal structure and the dynamics of the body.
The research activities of the Asterics group aim at understanding the evolution of stars and their dynamic processes thanks to Asteroseismology. Stellar magnetic fields, from the core to the envelope of the star, are at the center of the group’s research. So far, they have largely been excluded from stellar evolution models due to a lack of observation and of theoretical prescriptions. To make the necessary breakthrough on our understanding of poorly characterized but essential stellar magnetic fields, the group brings together in synergy observational constraints from Asteroseismology, modeling of stellar evolution, and theoretical prescriptions.
Red giant stars
Magnetoasteroseismology
L.Bugnet
Magnetoasteroseismology is the core expertise of the Asterics group. We develop theoretical predictions to search for magnetic field signatures on the oscillations of stars. All started on the red giant branch, where mixed acoustic-gravity modes allow us to probe deeply buried magnetic fields in the radiative interior.
Main sequence stars
Fossil field theory
The origin of magnetic fields observed in the core of red giant stars is still a mystery. We work on the fossil field theory, where magnetic fields resulting from dynamo action in the convective zone stabilize after the end of the convection and remain trapped inside stars for the rest of their evolution. The convective core of intermediate-mass main sequence stars is our key laboratory.
L. Barrault
Data analyses Methods for Asteroseismology
Developing new methods to automatically analyze asteroseismic data is at the core of the data analysis expertise of the group. In addition to classic asteroseismology methods, we develop Bayesian fitting & Machine learning tools to classify and analyze stars.
K. Smith
PLATO Mission
The group is working on the development of machine learning tools for the analysis of stars from the upcoming PLATO space Mission.