Using a range of detectors developed with the participation of the CEA, physicists at CEA-Irfu have scrutinized the region from which the gravitational wave was detected on August 17, 2017 by LIGO-VIRGO facilities. Unlike the four previous detections of waves of the same type discovered since 2015, this new vibration of space, called GW170817, is of different origin. It does not result from the fusion of two black holes but of two densest known stars, the neutron stars.