[Échos galactiques]Astrophysicist Annie Robin shines at the Academy of Sciences – Journal en direct

Both “surprised and very honored”, Annie Robin received the François-Dominique Arago medal from the Academy of Sciences last October in Paris. This remarkable distinction, specific to the field of astronomy and awarded by the prestigious institution only every four years, comes in 2024 to crown the exemplary career of the astrophysicist.

With the Besançon Observatory as her home base, with her eyes fixed on the celestial vault, Annie Robin has participated in the largest international research programs, with a view to always improving explore and know the Milky Way. Her investigations have taken her, among others, from the Canada-France-Hawaii Observatory, installed on the Polynesian island, to the European Southern Observatory (ESO) in Chile, via the Observatory of the Côte d’Azur in the South of France.

The “model of the Galaxy of Besançon”of which she is the main architect, is a essential scientific referenceknown and recognized by his peers throughout the world. This adventure began in the early 1980s with an idea of Michel Crézéwhich at the Observatory suggests bring together all the observations already made on the Milky Way into a statistical modelto develop simulations and verify hypotheses on training and development of our galaxy. A doctoral student under his supervision, Annie Robin tackles the task. At the end of 1983, after completing her thesis, she assembled all the existing pieces of the puzzle, which gave rise to the first version of the model.

Forty years later, this model still exists but it has been considerably enriched over the years, benefiting from advances in science both in the way of observing the stars and in the measurement of physical and chemical parameters making it possible to determine their age, their position, their orbit, their interactions… “Very quickly, we integrated theoretical elements which allowed us to helped us better understand our hypotheses. This is what establishes the particularity and interest of the model, the development of which is the work of an entire team, with Michel Crézé and Olivier Bienaimer first, then Céline Reylé, and numerous doctoral students,” says Annie Robin. , today emeritus research director at UTINAM.

The model of the Galaxy born from his thesis was used to build simulation tools to prepare for the Gaia satellite missionwhich for ten years has been collecting information from the heart of the Milky Way over incredible distances and with an astrometric precision 50 to 100 times greater than that of its predecessor, Hipparcos. The first European probe launched to explore our galaxy, Hipparcos already brought fantastic and unprecedented results from observations carried out from space in the 1980s, based on a directory of some 120,000 stars. Today, even before the end of its systematic observations planned for the beginning of the year, Gaia represents a census of 1.7 billion stars, which will lend themselves to the analysis of specialists for years.

The Bisontin model continues to play its role in this revolutionary configuration: by comparing its simulations to the data collected by Gaia, it helps validate observations made by the European satelliteahead of the publication of each of its star catalogs. The model of the Galaxy resulting from Annie Robin’s first research work continues to make shine the name of Besançon in the global astronomical sphere.