High-velocity line emission in the narrow-line region of NGC 4151

Narrowband imaging of the nuclear region of NGC 4151 with the Hubble Space Telescope is presented. The filter bandpasses isolate line emission in various high-velocity ranges in several ions. Slitless and long-slit spectra of the region with the Space Telescope Imaging Spectrograph also indicate the locations of high-velocity gas. These emission regions are faint and interspersed among the bright emission clouds seen in direct images. They have radial velocities up to 1400 km s(-1) relative to the nucleus and are found in both approach and recession on both sides of the nucleus. This contrasts strongly with the bright emission-line clouds, which have been discussed previously as showing bidirectional outflow with velocities within 400 km s(-1) of the nucleus. We discuss the possible connections of the high-velocity material with the radio jet and the nuclear radiation.