AAS Meeting #193 - Austin, Texas, January 1999
Session 65. Interstellar Dust and Gas
Display, Friday, January 8, 1999, 9:20am-6:30pm, Exhibit Hall 1

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[65.15] High-Resolution Optical Observations of Na I and Ca II Absorption in ORFEUS-SPAS I and II Stars and a measurement of the CO to H2 conversion factor toward the line of sight to HD 192575

N. Craig, W. V. Dixon, M. Hurwitz, H. Thai (SSL/UCB), T.P. Sasseen (UCSB), T. M. Dame (CfA/Harvard.U)

We present high-resolution spectroscopy (\lambda / \Delta \lambda ~60,000) of the interstellar Na I D and Ca II K lines in the spectra of 12 early-type stars in the Galactic disk (|z| <300 pc) at distances out to 3.9 kpc, obtained with the Shane 3-m Telescope at Lick Observatory. Velocities, column densities, and b values are derived for individual absorption components along these lines of sight. The data will become part of a catalog of optical measurements of the ISM, obtained with the Shane telescope and from the literature, toward the nearly sixty O and B-type stars observed with the Berkeley spectrometer on the ORFEUS-SPAS I and II space-shuttle missions. The catalog will support studies of molecular hydrogen absorption and interstellar reddening, among others, using the FUV spectra obtained with the ORFEUS telescope.

We present direct measurements of N(H2) and W(CO) along the line of sight to HD 192575 for which the optical data suggest that the star is more distant than the molecular gas, and arrive at a CO to H2 conversion factor of about 2 \times 1020~cm-2 per K km/s.

If you would like more information about this abstract, please follow the link to http://sag-www.ssl.berkeley.edu/orfeus. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

The author(s) of this abstract have provided an email address for comments about the abstract: ncraig@ssl.berkeley.edu

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