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Published April 1, 1976 | Published
Journal Article Open

Optical and infrared spectrophotometry of 18 Markarian galaxies


Slit spectra, spectrophotometric scans, and infrared broad-band observations are presented of 18 Markarian galaxies with emission lines. Eight of the program galaxies can be classified as Seyfert galaxies. Arguments are given that thermal, nonthermal, and stellar radiation components are present. Broadly speaking, one group of Seyfert galaxies is characterized both by the presence of a high-density region of gas and by a continuum dominated by nonthermal radiation. The continua of the remaining program Seyferts, which do not have a high density region of gas, are dominated by thermal radiation from dust and a stellar continuum. The 10 galaxies which are not Seyfert galaxies are shown to be examples of extragalactic H II regions; there is evidence for thermal emission from dust being present at 10 μ. in four of these galaxies.

Additional Information

© 1976 American Astronomical Society. Received 1975 August 21; revised 1975 September 17. We want to thank the night assistants of the Hale telescope, Gary Tuton and Juan Carrasco, for their help in obtaining these data as well as G. Garmire who collaborated in making the early infrared measurements and B. Turnrose and K. Matthews for their assistance. G. N. thanks the Guggenheim Foundation for a sabbatical fellowship and the Institute of Astronomy, Cambridge, for their hospitality; discussions with M. J. Rees were most helpful. We also thank J. Bennett and S. Hage for their help in preparing the data and this manuscript. Funds were provided by National Science Foundation grant MPS 74-18555 and by National Aeronautics and Space Administration grants NGL 05-002-207 and NGL 05-002-134.

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Published - 1976ApJ___205___29N.pdf


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