Digicon Spectrophotometry of the Quasi-Stellar Object PHL 957

Measurements of the spectral region centered on the broad La absorption in the QSO PHL 957 have been made with the UCSD Digicon (digital image tube) at the Cassegrain focus of the Lick 1204nch (305-cm) telescope, and photographic spectra have also been obtained over a wider spectral range. The broad absorption is very deep, with an intensity less than 2 percent of the continuum over the central 30 A. The profile of the broad absorption and the relationship between this feature and the other multiple-redshift systems found in PHL 957 by Lowrance et aA is discussed. Absorptions arising from excited fine-structure states of some ions may be present. If the central part of the La feature arises in the same gas as produces the C ii line at 4415 A, the C/H ratio may be lower than normal. Alternatively, most of the La broad absorption may consist of multiple La lines arising in a gas with a velocity range exceeding 1000 km -1 in which case C/H may be normal. Probably all the absorptions arise in gas associated with the QSO.