Cover: True colour image of the blue compact dwarf galaxy I Zw 18 (below) as seen by the
Advanced Camera for
Surveys on board of the Hubble Space Telescope, with visible filters (PI A. Aloisi). I Zw 18
is the most metal-poor starforming galaxy ever discovered, one of the closest
analogues to primordial galaxies. It has been often suggested that
it started to form stars only recently. The analysis of these data has shown that, contrary to previous suggestions, the galaxy hosts red giant branch stars, which are at least 2 billion years old (see joint NASA/ESA/INAF Press Release, 16 October 2007). These studies have been
performed by INAF-OAB scientists, in collaboration with colleagues from the STScI
(Baltimore, USA) and INAF-OA Capodimonte. Image Credit: NASA, ESA and A. Aloisi (STScI, ESA).
