2001ApJ...546L..97H

The nearby Seyfert galaxy NGC 7213 has been imaged in Hα and H I with the Cerro Tololo Inter-American Observatory 1.5 m telescope and with the Australia Telescope Compact Array, respectively. Optically, NGC 7213 looks undisturbed and relatively featureless, but the continuum-subtracted Hα image shows a 19 kpc long filament located approximately 18.6 kpc from the nucleus. The Hα filament could be neutral gas photoionized by the active nucleus, as has been suggested for the Seyfert galaxy NGC 5252 or shock-ionized by a jet interacting with the surrounding H I, as has been suggested for the radio galaxy PKS 2240-41. The H I map reveals NGC 7213 to be a highly disturbed system, suggesting a past merging event.