INTERSTELLAR ABSORPTION ALONG THE LINE OF SIGHT TO THETA-CARINAE USING COPERNICUS OBSERVATIONS

From Copernicus observations of the line of sight to theta Car, 61 atomic absorption lines of 12 elements were identified, along with 16 molecular hydrogen lines in the Lyman and Werner series. By using a profile-fitting technique rather than curves of growth, we were able to obtain column densities and Doppler b values for the H I and H II clouds which are present along this line of sight. Electron densities for both clouds were calculated from the ratios of the fine-structure levels of C II and N II, obtaining n(e(H I)) almost-equal-to 0.08 cm-3 and n(e(H II)) = 1.2 cm-3. The neutral hydrogen density was calculated for the H I region, using the fine-structure levels of C I, which led to n(H) = 120 cm-3 D I is also present in the data from the theta Car line of sight, giving a D/H ratio of 5 X 10(-6). In addition; elemental depletions were calculated for the H I region. When the results for theta Car were compared to those for zeta Oph and alpha Vir, the absolute depletions were different; however, the relative depletions (the element-to-element depletion patterns) were remarkably stable for different physical conditions.