High‐Resolution Spectra of Intrinsic Absorption Lines in the Quasi‐stellar Object UM 675

Abstract

We discuss high-resolution (D9 km s~1) Keck Observatory spectra of the associated absorp-(z a B z e ) tion lines in the QSO UM 675. In a previous paper we showed that the time-variable absorpz e \ 2.15 tion lines require a minimum gas density of D4000 cm~3 and a maximum distance of D1 kpc from the QSO. We also inferred metallicities of from an assortment of measured column densities. Z Z Z _ The new data yield absorption-line proles for Lya, and C IV, more reliable column densities, and evidence for partial coverage of the background emission source(s). The line proles are domiz a B z e nated by broad (FWHM B 470 km s~1) and relatively smooth components with centroids shifted roughly [1500 km s~1 from the emission-line redshift. Much weaker narrow-line components (with FWHM B 55 and 29 km s~1) are also detected inside the broad C IV and N V proles, but they contribute negligibly to the total equivalent widths and column densities. The complex of broad and narrow lines indicates formation in an outow, possibly in discrete ejection events, where distinct regions have the same outow velocity but di erent (nonthermal) velocity dispersions.