Absorption Lines in the Spectra of Quasistellar Objects

Abstract

We speculate that over the last decade more observing time on large telescopes has been spent on spectroscopy of QSO absorption lines than on any other program. Partly this reflects a desire to resolve the intense controversy that has arisen over the origin of QSO absorption lines, but it also reflects the realization that when the origins of these lines are fully understood, an enormous amount of information concerning the environ­ ment of QSOs and uncondensed intervening gas becomes available. The topic of QSO absorption (and emission) lines was last reviewed in this series by Strittmatter & Williams (1976). It has become almost ritualistic for reviewers of topics such as this to write that despite the enormous gain in the amount of observational material acquired, this material has raised more problems than it has answered and some basic questions remain unanswered. We concur. The large increase in both the quality and quantity of QSO absorption line data over the last four years has been in large measure due to the development of excellent high resolution detectors, e.g. the IPCS (Boksenberg 1972). We do sense as a result of these developments, however, a fairly strong shift in opinion about the origin of the absorption lines from that summarized by Strittmatter