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Session 28 -- QSO Absorption-Line Studies with HST and Keck

Oral presentation, Tuesday, June 13, 1995, 2:00pm - 5:30pm

[28.07] Constraints on Ly$\alpha$ Forest Cloud and Metal-Line Cloud Sizes and Shapes from HST-FOS Spectra of the Gravitationally Lensed QSO H1413+1143

We present preliminary results of an analysis of HST-FOS spectra for the separate components of the gravitationally lensed `Cloverleaf' QSO H1413+1143 (z$_{em}$ $\simeq$ 2.54). The G400H spectra cover the redshift range z $\sim$ 1.8 - 2.4 and probe the Ly$\alpha$ forest on size scales less than $\sim$4h$^{-1}_{100}$ kpc (q$_0$ = 0), while G570H spectra reveal the presence of metal-line systems at redshifts of z $\simeq$ 1.44 and 1.66 and probe similar size scales. Examination of how the equivalent widths correlate for lines of the component spectra can provide information about whether all four lines of sight to the QSO are passing through the same absorbing region, placing limits on cloud sizes and shapes. Studies of this type help to constrain models for the different cloud populations seen in QSO absorption spectra. The four sight lines toward the high redshift QSO H1413+1143 provide a unique geometry for this type of study.

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