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F.H. Chaffee (W.M. Keck Observatory), C.B. Foltz (National Science Foundation), R.J. Weymann (Observatories of the Carnegie Institution of Washington)
We present outflow velocity measurements of the BAL QSO 1303+308 taken over more than a twenty year baseline. This object exhibits complex absorption troughs in its near UV spectrum that are highly structured, containing a number of individual, resolved absorption doublets. Furthermore, a number of the absorption features have been reported to be ‘line-locked’ with the longer wavelength member of one doublet being coincident with the shorter wavelength member of another. Although detailed models are lacking, these coincidences have been used to infer that radiative acceleration plays a role in the dynamics of the absorbing gas. Observations of Q1303+308 were made in the 1980s and 1990s with the MMT spectrograph at a resolution of 60 km/sec and in the 21st century with HIRES on Keck I at a resolution of 5 km/sec. The elapsed time in the rest frame of the QSO (z=1.76) is approximately eight years. By comparing the N V, Si IV and C IV absorption complexes, we are able to set extremely stringent limits on the secular acceleration of the outflowing material. We also comment on changes in the equivalent widths of the absorption troughs over the elapsed time of the observations.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.