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Title: Dust in the nuclei of the Seyfert galaxies Markarian 231 and NGC 4151

Observations carried out with a 8-13 micron grating-spectrometer of Mrk 231 and NGC 4151 are reported. The Mrk 231 data can be fitted to various thermal dust emission models or a single power law, with dust extinction. In all the model fits, except for that of graphite and silicon carbide grain emission, a component of silicate absorption of optical depth of not more than 0.7 is required. Confirming published work, the absorption being at the redshift of the low-redshift absorption-line system is ruled out. The high values of silicate optical depth absorption do not give ratios to the galaxy's visual extinction which are comparable to those of galactic H II regions. Weak evidence for a 10-micron absorption feature in NGC 4151 is also reported. This is somewhat contrary to expectation, since the visual extinction of NGC 4151 is lower than that of Mrk 231, and since there is evidence to support a nonthermal rather than thermal dust origin for the infrared continuum emission. 46 references.
Authors:
; ; ;
Publication Date:
OSTI Identifier:
6094894
Resource Type:
Journal Article
Resource Relation:
Journal Name: Publ. Astron. Soc. Pac.; (United States); Journal Volume: 96
Research Org:
Hawaii Univ., Mauna Kea
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; SEYFERT GALAXIES; COSMIC DUST; GALAXY NUCLEI; ABSORPTION; INTERSTELLAR SPACE; DUSTS; GALAXIES; SPACE 640105* -- Astrophysics & Cosmology-- Galaxies