The distribution and kinematics of interstellar O~{\small VI} in the Milky Way}

TL;DR

This study surveys interstellar O VI absorption in the Milky Way using FUSE data towards 69 stars in the LMC, revealing its distribution, kinematics, and variations on multiple scales, indicating turbulence and complex cloud structures.

Contribution

First comprehensive analysis of interstellar O VI distribution and kinematics in the Milky Way using FUSE data towards LMC stars, highlighting scale-dependent variations and cloud components.

Findings

O VI column densities range from 13.68 to 14.73 log units.

O VI exponential scale height is approximately 2.28 kpc.

Velocity dispersion indicates turbulence and multiple components.

Abstract

We present the results of a survey of interstellar O~{\small VI} absorption in the Milky Way (MW) towards {69} stars in the Large Magellanic Cloud (LMC) obtained with the \textit{Far Ultraviolet Spectroscopic Explorer (FUSE)}. The integrated MW O~{\small VI} column densities log N(O~{\small VI}) are in the range from 13.68 to 14.73 with a mean of {14.26$_{-0.09}^{+0.07}$} atoms cm$^{-2}$. The O~{\small VI} exponential scale height is found to be {2.28$\pm$1.06} kpc. The O~{\small VI} column density correlates with the Doppler parameter $\it b$. The O~{\small VI} velocity dispersion ranges from {14.0 to 91.6 with an average value of 62.7 km s$^{-1}$}. These high values of velocity dispersion reveal the effect of turbulence, multiple velocity components and collision on broad O~{\small VI} profiles. There is a significant variation of O~{\small VI} column density on all scales studied {(0.0025$\degr$ - 6.35$\degr$)}. The smallest scale for which O~{\small VI} column density variations has been found is {$\bigtriangleup \theta$ $\sim$~9$\arcsec$}. Comparison of the O~{\small VI} velocity profiles with Fe~{\small II} indicates the presence of intermediate velocity cloud (IVC) and/or high velocity cloud (HVC) components in the O~{\small VI} absorption.