Far-ultraviolet spectrum of the Seyfert galaxy NGC 4151
Abstract
The emission and absorption lines detected in a far-UV spectrum of the Seyfert galaxy NGC 4151 are described. The spectrum was obtained over the wavelength range from 1160 to 1760 A with a resolution of about 8 A using a rocketborne faint-object telescope. It is found that Ly-alpha is the strongest emission line in the far-UV spectrum but, relative to the optical emission-line strengths, is much weaker than predicted by theoretical calculations of radiative recombination in the photoionized gas in a Seyfert nucleus. Other features discussed include H-beta, C IV at 1550 A, and He II at 1640 A, as well as absorption features ascribed to Si II at 1260 A and C II at 1335 A. Intensity ratios similar to those deduced for quasars in general are determined, and the large column density suggested by the absorption lines is shown to be consistent with observations of strong X-ray absorption corresponding to a hydrogen column density of approximately 10 to the 23rd power per sq cm in NGC 4151.
- Publication:
-
COSPAR, 21st Plenary Meeting
- Pub Date:
- May 1978
- Bibcode:
- 1978cosp.meetQ....D
- Keywords:
-
- Far Ultraviolet Radiation;
- Seyfert Galaxies;
- Stellar Spectrophotometry;
- Ultraviolet Spectra;
- X Ray Sources;
- Absorption Spectroscopy;
- Line Spectra;
- Tables (Data);
- Ultraviolet Astronomy;
- Astronomy