Interstellar Turbulence in the WarmIonized Medium using Emission LinesBy

The nature of turbulence in the warm ionized component of the interstellar medium (WIM) can be investigated using Fabry-Perot spectroscopy of optical emission lines. The H intensity provides the emission measure (EM) along a line of sight, which is used in conjunction with the scattering measure, rotation measure, and dispersion measure to study interstellar turbulence. Observations at high spectral resolution (10 km s ?1) allow measurements of the bulk radial velocity structure of the emitting gas and investigations of thermal and non-thermal (turbulent) broadening mechanisms through the line widths. By measuring the widths of the H line and an emission line from a heavier atom (e.g. the S II 6716 line), one can separate the thermal and non-thermal contributions to the line width. Preliminary studies using this method have shown that the broad range of H line widths (typically 15 { 50 km s ?1) is mostly due to diierences in the non-thermal component of the width and that along many lines of sight this component dominates. The Wisconsin H Mapper (WHAM) is in the process of producing a very sensitive kinematic map of the northern sky in H at 1 o angular resolution and 12 km s ?1 spectral resolution. WHAM is also mapping emission lines from heavier atoms such as sulfur and nitrogen for selected regions of the sky. This data set will provide unique new information concerning turbulence in the WIM.