Diffuse Ionized Gas (DIG) in Edge-on Spirals. Deep imaging of DIG layers in edge-on spirals is continuing at the KPNO 0.9-m. Deep spectroscopy at the KPNO 4-m is continuing, with the goal of understanding more about the ionization, extent and kinematics of DIG layers. Future goals in this area include new, substantially deeper, imaging techniques, and a spectroscopic search for DIG beyond truncated edges of HI disks.
Molecular Gas Layers in Edge-on Spirals. BIMA is being used to map CO in one field in NGC 891, in order to understand how uv-coverage affects vertical extents of molecular layers inferred from interferometric observations. CO and HCN observations of NGC 4631 have also been obtained and are being analyzed.
Molecular Gas and Star Formation in Spirals. Mapping of CO in the nearby spirals M83 and NGC 6946 is continuing at the OVRO and BIMA millimeter inferferometers, respectively, in order to understand how molecular gas responds to spiral density waves, triggering of star formation, and production of HI by dissociation of molecular gas, among other issues.