IUE observations of Markarian 3 and 6 : reddening and the nonstellar continuum.

Abstract

The authors have used IUE visual and infrared observations to study the spectra of the Seyfert 2 galaxies NGC 1068 and Markarian 3, and the Seyfert 1.5 galaxy Markarian 6. The starlight in these galaxies is reddened by 0.01, 0.18, and 0.06 mag in E_B-V, respectively; the forbidden lines are reddened by 0.29, 0.27, and 0.27 mag, respectively. A nonstellar component contributes 15, 20, and 30% of the visual flux, respectively, in NGC 1068, Mrk 3, and Mrk 6, in a 14arcsec aperture. It has a significant flux in the near-infrared and in the far-ultraviolet, and is well described by a power law with a slope of ≡ -1.1 in all three galaxies. The Seyfert 2's have warm dust which emits a large thermal infrared flux. If the central continuum heats this dust, it must be reddened by 0.3 and 0.5 mag or more in NGC 1068 and Mrk 3.