NGC 5252 - a Liner undercover

Abstract

Ground based long slit spectroscopic observations of the nuclear region of NGC 5252, and Hubble Space Telescope (HST) Faint Object Spectrograph (FOS) spectra of the nucleus and two bright knots located 0.36" NE and 0.31" SW from it, show that the nuclear region exhibits the characteristics of a Liner with exceptionally strong [OI] emission, all lines being broad (FWHM ~ 1100 km/s), while the gas outside the nucleus has a typical Seyfert 2 spectrum with relatively narrow lines (FWHM ~ 200-300 km/s). We suggest that all the emitting gas is photoionized by the hidden non-thermal nuclear source detected through near-infrared (Kotilainen & Prieto 1995) and X-ray (Cappi et al. 1996) observations, the ionizing continuum, in the case of the central Liner, being "filtered" by a matter-bounded highly ionized cloud, hidden from our view by the same material obscuring the central continuum source.