I study how stars, like our own sun, are born.

To do so, I use telescopes to look at the sky, and observe the embryos of stars that are forming, in our Milky Way.

I try to understand how the Universe is transforming the cold gas, present in the interstellar medium of our Galaxy, into dense structures that collapse and ultimately form young stars.

I study how multiple stellar systems are formed, as well as how disks are built during the star formation process, and eventually fragment into planetary systems, like our own around the sun.

I also try to understand the roles of turbulence and magnetic fields in the process of forming stars.

Rotation is everywhere in astrophysical structures, and prestellar cores have also been shown to contain angular momentum. The conservation of the core s angular momentum during the accretion of core material to the embryo protostellar object in its center should result in most of the core s angular momentum to be channeled into the forming star. It has been shown that the speed at which the resulting star would rotate is not sustainable and well above break-up speed. The evolution and distribution of initial core’s angular momentum during star formation process has to be studied in details, or else we can not explain the formation of the most basic bricks of the Universe: solar-type stars.

Moreover, in our own solar system, while most of the mass was indeed channeled to the central star, our Sun, the distribution of angular momentum is very different from the mass distribution: it is the Jovian planets who got the biggest slice of the angular momentum cake.

Physical processes should therefore be found to redistribute angular momentum from the inner parts to the outer parts of the protostellar envelope during the star formation process. The problem is quite severe: one core should reduce its specific angular momentum by 5 to 10 orders of magnitude to form a typical star such as our Sun.

In the standard paradigm of star formation, it is believed that the formation of disks and/or the fragmentation of cores into multiple protostellar systems would allow to alleviate the angular momentum problem. But other ingredients, such as turbulence and magnetic fields, could also play a major role in shaping the accretion processes and therefore drive angular momentum re-distribution and evolution.

The question of how exactly the angular momentum problem is solved during the star formation process is still extensively debated. Beyond solving this open issue, characterizing which physical processes play a key role in turning a prestellar core into a young star also addresses directly our quest for understanding how accretion proceeds to turn ISM material into a range of stellar masses (CMF/IMF) but also how multiple stellar systems, disks, and ultimately planets, form. Answers to these questions lie in high-resolution comprehensive studies of protostellar objects during the main accretion phase: Class 0 protostars.