Faint Object Spectrograph Spectra of the UV Emission Lines in NGC 5548: Detection of Strong Narrow Components
Abstract
Ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 were obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope on 1992 July 5, when the UV continuum and broad emission lines were at their lowest ever observed level. The high resolution of the spectra, relative to previous UV observations, and the low state of NGC 5548 allow the detection and accurate measurement of strong narrow components of the emission lines of Lyα, C IV λ 1549, and C III] λ1909. Isolation of the UV narrow components enables a detailed comparison of narrow-line region (NLR) properties in Seyfert 1 and 2 galaxies, and removal of their contribution is important for studies of the broad-line region (BLR). Relative to the other narrow lines, C IV λ 1549 is much stronger in NGC 5548 than in Seyfert 2 galaxies, and Mg II λ2798 is very weak or absent.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1993
- DOI:
- 10.1086/187072
- Bibcode:
- 1993ApJ...416L..67C
- Keywords:
-
- GALAXIES: INDIVIDUAL NGC NUMBER: NGC 5548;
- GALAXIES: SEYFERT