The HST Quasar Absorption Line Key Project. IX. an Emission-Line Study of PG 2251+113
Abstract
We present HST and quasi-simultaneous ground-based observations of the z = 0.3252 QSO PG 2251 + 113. We find a correlation between line widths and the critical density for de-excitation of the forbidden emission lines observed in this object. We can show that this correlation also applies to the semiforbidden and possibly also the permitted lines which arise in the broad emission-line region. While this result was predicted from statistical studies, it has never previously been shown to hold in detail in any individual object. This relationship between the narrow and broad emission-line regions may help constrain dynamical models of both regions. We examine the implications of this result for a simple radial infall model of the emitting gas developed to explain the origin of narrow-line profiles.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1994
- DOI:
- Bibcode:
- 1994ApJ...434..484E
- Keywords:
-
- Absorption Spectra;
- Emission Spectra;
- Forbidden Bands;
- Line Shape;
- Quasars;
- Ultraviolet Astronomy;
- Ultraviolet Spectra;
- Visible Spectrum;
- Astronomical Models;
- Carbon;
- Computerized Simulation;
- Hubble Space Telescope;
- Iron;
- Neon;
- Oxygen;
- Astrophysics;
- GALAXIES: QUASARS: ABSORPTION LINES;
- GALAXIES: QUASARS: INDIVIDUAL ALPHANUMERIC: PG 2251;
- 113;
- ULTRAVIOLET: GALAXIES