Emission-line widths in galactic nuclei.
Abstract
Line width measures for the forbidden O III emission lines have been obtained for 116 galactic nuclei with instrumental resolution of 165 km/sec. Galaxies observed include 53 Seyfert 1 galaxies, 16 Seyfert 2 galaxies, and 47 star-burst galaxies for which the nuclear emission lines are attributed to ionization by hot, short-lived stars. The median FWHM for the forbidden O III lines is 375 km/sec for Seyfert 1, 510 km/sec for Seyfert 2, and 160 km/sec for star-burst nuclei. It is suggested that an empirical criterion for dividing Seyfert galaxies from other emission line galaxies is a FWHM greater than 250 km/sec for the forbidden O III lines. From dynamical arguments, the star-burst nuclei are determined to have the star formation activity restricted to a nuclear disk with radius less than a few hundred parsecs.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1982
- DOI:
- 10.1086/159919
- Bibcode:
- 1982ApJ...256..427F
- Keywords:
-
- Emission Spectra;
- Galactic Nuclei;
- H Beta Line;
- Oxygen Ions;
- Seyfert Galaxies;
- Spectral Line Width;
- Astronomical Spectroscopy;
- Forbidden Bands;
- Galactic Structure;
- Hot Stars;
- Spectral Resolution;
- Astronomy