Research

Othman Benomar's research focuses on the evolution and characterisation of low-mass stars. He also studies the interplay between exoplanets and their host stars. His current main researches are on the measure of the stellar rotation by the means of asteroseismology, and on the spin-orbit angle of exoplanets.

Stars are elementary components of the universe and their prodigious number in the universe give us the opportunity to use them as laboratories to test, a wide range of physics processes (e.g. heat transfer, plasma hydrodynamics, nuclear fusion reaction) in extreme conditions of temperature and pressure.

Understanding the physics of stars is also of great importance to study how the exoplanets are formed and to determine conditions for life to exist on those exoplanets. We discover every day new planets around distant stars. For example, to measure their masses and orbits, we need to precisely know the mass and radius of the host-star.

However, stars are very distant, dense and opaque objects, for which in-situ measurement is not possible, and thus are a challenge to study. But using seismic waves that propagate within stars, one can reveal their internal structure. Like in a bell, these waves resonate and the star pulsates at very specific frequencies that depends on the nature of its interior (e.g. pressure, density, temperature, internal rotation). The science that studies these seismic waves is called asteroseismology. Asteroseismology is thus very similar to earth seismology that allows geophysicists to infer the internal structure of earth using earth quakes.

For decades, asteroseismology was only possible for the Sun and on few massive stars. Now, with the space-borne instruments CoRoT (CNES, FRANCE, launch in 2007) and Kepler (NASA, USA, in 2010), it is possible to test on hundreds of thousand stars, the theory of structure and of the evolution of stars. Furthermore, new projects in preparation (TESS, PLATO, SONG) announce a change of paradigm regarding our understanding of stars within our galaxy.