IZW18 and the Search for Very Metal Poor Galaxies

Abstract

As Lequeux has pointed out during his talk, the blue dwarf compact galaxies are experiencing strong star formation processes at present time. Nevertheless they appear to be metal deficient and gas rich. These properties led to some controversy about the very nature of these objects. One can argue that in order to maintain a low overall metallicity the averaged star formation rate must be kept quite low. A series of bursts of star formation separated by long quiescent periods would meet the requirements and the age of the galaxies can be normal. On the other hand these objects can be genuinely young namely undergo their first burst of star formation. The debate is not yet closed and I propose here to add a bit by speculating about the rarety of objects like IZW18.