Mapping distant galaxies

Three examples of results obtained with GIRAFFE on distant galaxies. In the first column, images of galaxies as obtained with the Hubble Space Telescope are shown. The second column is the velocity field as deduced from GIRAFFE observations : the reddish parts show material moving away from us with respect to the mean velocity of the galaxy, while the blue parts are moving towards us. The scale in km/s is shown on the right. The last column is a map of electron density per cubic centimetre. The first object corresponds to a spiral galaxy forming star at a frantic rate of 100 solar masses per year. The electron density map allows the astronomers to localise the region of star formation as the black region on the left. The second object is a galaxy which is clearly "out of balance" and therefore shows a very perturbed velocity field. The third object appears to show an outflow — matter being ejected perpendicular to the plane of the galaxy.