This paper describes observations of interstellar CH+ along the lines of sight to O and B stars with E(B - V)s up to +1.13. Along some lines of sight with strong detections of CH+, we find distinct radial velocity shifts between the CH+ lines and other neutral species, such as Ca I and CH. The shifts are small but are predicted by shock models of CH+ formation in which the shock is inclined with respect to the observer. We have also found no column densities exceeding approximately 10(13.8) cm-2. When these data are examined along with other CH+ data collected from the literature, the previously seen tendency of CH+ column density to increase with E(B - V) does not continue beyond reddenings of about +0.6. These findings offer support to the shock model of CH+ formation for at least some lines of sight.

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.

In this paper, we report on observations of CH+ and other species accessible in optical wavelengths in the line of sight to HD 190603, a B1.5 lae supergiant. In this line of sight we see a shift in radial velocity between the CH+ line and other interstellar absorption lines such as CH and Ca I. The most likely explanation for this effect is the shock formation of CH+. We also make some estimates of likely preshock and postshock conditions which are consistent with the observations.

view Abstract Citations (18) References (55) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Interstellar Absorption along the Line of Sight to sigma Scorpii Using Copernicus Observations Allen, M. M. ; Snow, T. P. ; Jenkins, E. B. Abstract From Copernicus observations of Sigma Sco, 57 individual lines of 11 elements plus the molecular species H2 and CO were identified. By using a profile-fitting technique, rather than curves of growth, it was possible to obtain column densities and Doppler b values for up to four separate components along this line of sight. Electron density in the major H I component was derived from the photoionization equilibrium of sulfur, obtaining, n(e) of about 0.3/cu cm. The neutral hydrogen density in the same component was also derived using fine-structure excitation of O I. An H II component is also present in which the electron density was n(e) about 20/cu cm. As a by-product of this analysis, previously undetermined oscillator strengths for two Mn II lines were obtained: for 1162.-017 A, f about 0.023 and for 1164.211 A, f about 0.0086. Publication: The Astrophysical Journal Pub Date: May 1990 DOI: 10.1086/168747 Bibcode: 1990ApJ...355..130A Keywords: Abundance; Astronomical Spectroscopy; Interstellar Extinction; Interstellar Matter; H I Regions; Molecular Spectra; Oao 3; Scorpius Constellation; Astrophysics; INTERSTELLAR: ABUNDANCES; INTERSTELLAR: MATTER full text sources ADS | data products SIMBAD (4) MAST (1) Related Materials (1) Erratum: 1990ApJ...364..335A

view Abstract Citations (40) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Far-Ultraviolet Extinction Determined from Voyager Data Snow, Theodore P. ; Allen, M. M. ; Polidan, R. S. Abstract Data from the Voyager UV spectrometers are used to derive FUV extinction curves for 19 stars, using the pair-comparison method after the removal of the effects of line absorption due to H I and H2. It is shown that the FUV extinction rise continues to the limit of the data at about 925 A, supporting the theoretical prediction by Longo et al. (1989) that the FUV extinction continues to rise toward short wavelengths all the way to the Lyman limit at 912 A. Publication: The Astrophysical Journal Pub Date: August 1990 DOI: 10.1086/185787 Bibcode: 1990ApJ...359L..23S Keywords: Cosmic Dust; Far Ultraviolet Radiation; Interstellar Extinction; Interstellar Matter; Ultraviolet Spectrometers; Voyager Project; Absorption Spectra; H I Regions; H Ii Regions; Line Spectra; Astrophysics; INTERSTELLAR: GRAINS; INTERSTELLAR: MATTER full text sources ADS | data products SIMBAD (19)

Since the launch of Copernicus in 1972, studies have been made of the depletion of gas-phase elements onto dust grains. A few stars have been studied in detail, resulting in a standard depletion pattern which has since been used for comparison. Recent developments, however, have suggested that this standard pattern may need to be re-examined. Some weak, semi-forbidden lines were detected recently which may be able to resolve some of the ambiguities. Studies of single elements have shown that depletion of carbon and oxgyen are much smaller than previously determined. The high resolution ultraviolet spectral scans of sigma Sco were originally made in 1973, but have only recently been analyzed. All these stars are bright and moderately reddened. All four stars will be analyzed in detail, but sigma Sco is the first one completed. The data has broad coverage of ions, making these stars excellent candidates for determination of accurate depletions. A profile-fitting analysis was used rather than curves-of-growth in order to determine separate abundances and depletions in components separated by several km/sec.