Hot Gas in the ISM: A Reanalysis of Interstellar O$^{+5}$
Session 41 -- EUVE -- Astronomy
Display presentation, Tuesday, 6:00-8:00, CEA Room

## [41.28] Hot Gas in the ISM: A Reanalysis of Interstellar O$^{+5}$

R. L. Shelton (U. W. Madison), D. P. Cox (U. W. Madison)

Interstellar material with $T \sim 10^{5.5}$ K is well traced by the \oxyfive\ ion. By reanalyzing the Copernicus column densities toward 72 stars, with adjustments for the \lb\ and with slight improvements in the statistical approach originally used by Jenkins, we came to distinctly different conclusions. \begin{enumerate} \item The \oxyfive\ bearing material is probably clumped into features of much larger column density than estimated by Jenkins (2 to 7 $\times 10^{13}$ \oxyfive\ ions cm$^{-2}$ versus 1 $\times 10^{13}$ cm$^{-2}$), \item Our value for the mean \oxyfive\ volume density in the midplane is smaller (1.15 to 2.1 $\times 10^{-8}$ cm$^{-3}$ versus Jenkins's 2.8 $\times 10^{-8}$ cm$^{-3}$), \item The mean line of sight distance between features is thus several times that of Jenkins: (450 to 1350 pc versus 165 pc), and \item The combined mean column density of the \lb\ and it's interface with the Local Cloud is roughly 1.7 $\times 10^{13}$ cm$^{-2}$. \end{enumerate} These changes influence our understanding of the morphology of the interstellar medium and the mechanisms which maintain that morphology.