The extended narrow line region of NGC 4151. I - Emission line ratios and their implications

M. V. Penston, A. Robinson, D. Alloin, I. Appenzeller, I. Aretxaga, D. J. Axon, T. Baribaud, P. Barthel, S. A. Baum, C. Boisson, A. G. de Bruyn, J. Clavel, L. Colina, M. Dennefeld, A. Diaz, M. Dietrich, F. Durret, J. E. Dyson, P. Gondhalekar, E. van GroningenP. Jablonka, N. Jackson, W. Kollatschny, E. Laurikainen, A. Lawrence, J. Masegosa, I. McHardy, E. J. A. Meurs, G. Miley, M. Moles, P. O'Brien, C. O'Dea, A. del Olmo, A. Pedlar, J. Perea, E. Perez, I. Perez-Fournon, J. Perry, G. Pilbratt, M. Rees, I. Robson, P. Rodriguez-Pascual, J. M. Rodriguez Espinosa, M. Santos-Lleo, R. Schilizzi, G. Stasińska, G. M. Stirpe, C. Tadhunter, E. Terlevich, R. Terlevich, S. Unger, V. Vila-Vilaro, J. Vilchez, S. J. Wagner, M. J. Ward, G. J. Yates

Research output: Contribution to journalArticlepeer-review


The paper presents the first results from long-slit spectra of the Seyfert galaxy NGC 4151 which give average diagnostic ratios of weak lines in the Extended Narrow Line Region (ENLR) of the galaxy and the first direct density measurement in an ENLR. These data confirm that the ENLR is kinematically undisturbed gas in the disk of the galaxy which is illuminated by an ionizing continuum stronger by a factor of 13 than a power law interpolated between recently observed ultraviolet and X-ray fluxes. Explanations of this apparent excess include a hot thermal continuum, time variations, and an anisotropic rotation field.
Original languageEnglish
Pages (from-to)53-62
JournalAstronomy and Astrophysics
Publication statusPublished - 1 Sep 1990


  • Emission Spectra
  • Galactic Radiation
  • Interstellar Matter
  • Line Spectra
  • Seyfert Galaxies
  • Anisotropy
  • Brightness Distribution
  • Radiation Distribution
  • Spectrum Analysis


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