A Retrospective Introduction

Abstract

“It takes little talent to see clearly what lies under one’s nose, a good deal of it to know in which direction to point that organ.” W. H. Auden Listening to the sequence of fine talks that have made up this Joint Discussion, I have been impressed by the veritable flood of new observations that bear on the question of the abundance ratios in the oldest stars. The flood is marked by depth and diversity, as ‘noses’ are being pointed in highly profitable directions. As an example of depth, I would note the extensive investigations reviewed by Andy McWilliam of the chemical compositions of very metal-poor stars where [Fe/H] ≃ -3 marks the upper end of the range defining the class. To characterize diversity, I draw attention to the analyses of quasar absorption line systems so ably discssed by Limin Lu who showed that the abundance ratios for the gas in such high z systems resemble ratios found from Galactic metal-poor stars. Of course, to many at this Joint Discussion the wealth and diversity did not come as a surprise. Indeed, I suspect that many of us pursue the topic of the composition of the first generations of stars because of the wealth and diversity of observational constraints that may now spawn a unified interpretation. Hopefully, the marvellous talks given here will pull in a few new minds - young and old - to ponder nucleosynthesis in very young galaxies and in our Galaxy in particular.