Bibcode
                                    
                            Penston, M. V.; Robinson, A.; Alloin, D.; Appenzeller, I.; Aretxaga, I.; Axon, D. J.; Baribaud, T.; Barthel, P.; Baum, S. A.; Boisson, C.; de Bruyn, A. G.; Clavel, J.; Colina, L.; Dennefeld, M.; Diaz, A.; Dietrich, M.; Durret, F.; Dyson, J. E.; Gondhalekar, P.; van Groningen, E.; Jablonka, P.; Jackson, N.; Kollatschny, W.; Laurikainen, E.; Lawrence, A.; Masegosa, J.; McHardy, I.; Meurs, E. J. A.; Miley, G.; Moles, M.; O'Brien, P.; O'Dea, C.; del Olmo, A.; Pedlar, A.; Perea, J.; Perez, E.; Perez-Fournon, I.; Perry, J.; Pilbratt, G.; Rees, M.; Robson, I.; Rodriguez-Pascual, P.; Rodriguez Espinosa, J. M.; Santos-Lleo, M.; Schilizzi, R.; Stasińska, G.; Stirpe, G. M.; Tadhunter, C.; Terlevich, E.; Terlevich, R.; Unger, S.; Vila-Vilaro, V.; Vilchez, J.; Wagner, S. J.; Ward, M. J.; Yates, G. J.
    Referencia bibliográfica
                                    Astronomy and Astrophysics (ISSN 0004-6361), vol. 236, no. 1, Sept. 1990, p. 53-62.
Fecha de publicación:
    
                        9
            
                        1990
            
  Número de citas
                                    122
                            Número de citas referidas
                                    115
                            Descripción
                                    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.