The Alpha Centauri System 

Towards new worlds

A tribute to Frédéric Thévenin's Career

The Alpha Centauri system is the reference system for comparative exoplanetology and stellar physics. Due to its proximity and the multitude of possible observation techniques such as asteroseismology, interferometry and astrometry, this triple stars is  certainly the best known beyond the Sun. Each star in the system has its particularity: the primary component A is very similar to the Sun, a dwarf G too, slightly more massive and evolved, which allows us to test our models of stellar structure and evolution, in particular to improve our knowledge of convective cores, and this for a star with known fundamental parameters of incomparable precision. The secondary component B, a dwarf K, colder and smaller but with a much more active magnetism allows a study of magnetism and stellar coronas, again with a very precise knowledge of the fundamental parameters, leaving little room for inaccuracy. Finally, after a few false detections, the system has experienced a strong resurgence of interest in recent years thanks to its smallest component, Proxima Centauri, a red dwarf around which several planets have been discovered, two confirmed telluric ones. For the moment all discovered in radial velocities, these planets can be scrutinized by the most modern instruments, HST, ALMA and soon with the JWST in order to obtain the counterpart in transits and especially for a better knowledge of their fundamental planetary parameters. and atmospheres, habitability for possible discovery of biomarkers.

The planets around the primary components begin to show their existence and open the way to the search for habitable worlds around our near (distance but also similarity) neighbor.

One of the questions that remains unanswered is to understand why the star system closest to us took so long to present its planets to us, almost 30 years after the first discovery of an exoplanet. This raises the question of the formation and stability of exoplanets in multiple systems. 

One of the attractions of this system is also the great conjunction that will take place in 2028 between the A component and a star in the deeper field. In addition to the fact that this could be an opportunity to observe a spatially resolved gravitational micro lens, this event would also allow us to detect other exoplanets by gravitational disturbances.

The aim of this workshop is to gather experts in various field (stellar and exoplanet) to share expertise to improve our knowledge of the system and define the route for detection and characterization of the new worlds in the coming years.

Lionel Bigot (chair), Pierre Kervella, Orlagh Creevey, François Bouchy, Lisa Kaltenegger, Meridith Joyce, Anne-Lise Maire (The Scientific Organizing Committee)