Le 24 mai 2013
À 10h30
Salle de Cours – Grande Coupole
Stacy McGAUGH
Case Western Reserve University, USA
Recent observations have revealed many new low surface brightness galaxies in the local universe. These objects provide unique insights into the evolution of galaxies. Pressing into the regime of zero optical surface brightness, a 21 cm survey conducted with the Green Bank Telescope has revealed the presence of HI clouds in the region between M31 and M33. The nature of these clouds is unclear. They might be recent condensations of intergalactic gas, primordial dwarf irregular galaxies that never formed stars, or some form of tidal debris. None of these interpretations are completely satisfactory. Apparently there remains much to be discovered, even in the Local Group.