Nuclear Physics Division

An international team led by astrophysicists from the Lyon Observatory (CRAL, CNRS/INSU, Université Lyon 1) and the AIM laboratory (CEA-Irfu, CNRS, Université Paris 7) has just shed some light on the origins of the giant gas ring in Leo.  The astrophysicists were able to detect an optical counterpart to this cloud, which corresponds to stars in formation, using the Canada-France-Hawaii telescope (INSU-CNRS, CNRC, U. Hawaii). The scientists then carried out numerical simulations on the supercomputers at the CEA and suggested a scenario for the formation of this ring. This involved a violent collision between two galaxies. The researchers were able to identify the galaxies involved in the collision and estimate the date of impact. This discovery supports the assertion that the gas in the ring is not primordial, but of galactic origin. This work was published in Astrophysical Journal Letters.