We present observations of probable line-of-sight acceleration of a broad absorption trough of C iv in the quasar SDSS J024221.87+004912.6 .
We also discuss how the velocity overlap of two other outflowing systems in the same object constrains the properties of the outflows .
The Si iv doublet in each system has one unblended transition and one transition which overlaps with absorption from the other system .
The residual flux in the overlapping trough is well fit by the product of the residual fluxes in the unblended troughs .
For these optically thick systems to yield such a result , at least one of them must consist of individual subunits rather than being a single structure with velocity-dependent coverage of the source .
If these subunits are identical , opaque , spherical clouds , we estimate the cloud radius to be r \simeq 3.9 \times 10 ^ { 15 } cm .
If they are identical , opaque , linear filaments , we estimate their width to be w \simeq 6.5 \times 10 ^ { 14 } cm .
These subunits are observed to cover the Mg ii broad emission line region of the quasar , at which distance from the black hole the above filament width is equal to the predicted scale height of the outer atmosphere of a thin accretion disk .
Insofar as that scale height is a natural size scale for structures originating in an accretion disk , these observations are evidence that the accretion disk can be a source of quasar absorption systems .
Based on data from ESO program 075.B-0190 ( A ) .