ARE THERE ANY YOUNG GALAXIES IN OUR LOCAL UNIVERSE?

摘要

We find no evidence for the presence of genuinely young galaxies in our Local universe. We argue that the metal deficiencies and the behavior of the N/O and C/O ratios meet several plausible explanations involving the primary and secondary nature of these elements and their dispersion and mixing by massive stars and intermediate mass stars. Colors are to be analysed using surface photometry and comparing several model scenarios since an instant burst model unavoidably provides a lower limit to the age. Ultimately colour-magnitude diagram techniques will be the only direct test to be performed at least on a small number local starburst galaxies. Our present analysis provides important warning for assessing the true age of distant galaxies.