Detection of Mid-Infrared Fine Structure Lines in NGC 1068
Session 59 -- Low Luminosity AGNs and Active Galaxies
Display presentation, Thursday, 2, 1994, 9:20-6:30

## [59.09] Detection of Mid-Infrared Fine Structure Lines in NGC 1068

J. W. Miles (National Air and Space Museum), J. R. Houck, T. L. Hayward (Cornell University)

We have detected the infrared fine structure transitions of [ArIII] 9.0~$\mu$m, [SIV] 10.5~$\mu$m, and [NeII] 12.8~$\mu$m in the Seyfert 2 galaxy NGC~1068. The observations were made with a spectral resolution of $\lambda/\Delta\lambda = 2000$ using the Cornell built instrument SpectroCam-10 at the Palomar Observatory 5~m telescope. The IR fine structure lines are normally collisionally excited and optically thin, so they are excellent probes of the physical conditions in the ISM. In addition, they are less affected by extinction than optical lines and can yield information on even the most heavily obscured regions. While most IR fine structure lines are inaccessible from the ground, our results demonstrate the ability of ground-based telescopes to measure at least a few of these lines for use as diagnostics of activity in galaxies. Extending this work to the dusty infrared luminous galaxies may help to answer the question of whether they are powered by AGNs or starbursts.