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For refcode 1989ApJS...70..271B:
Retrieve 129 NED objects in this reference.
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Copyright by American Astronomical Society. Reproduced by permission
1989ApJS...70..271B THE WASILEWSKI SAMPLE OF EMISSION-LINE GALAXIES: FOLLOW-UP CCD IMAGING AND SPECTROSCOPIC AND IRAS OBSERVATIONS GREGORY D. BOTHUN Department of Astronomy, The University of Michigan JULES P. HALPERN Department of Physics, Columbia University CAROL J. LONSDALE Infrared Processing and Analysis Center, Jet Propulsion Laboratory; and California Institute of Technology CHRIS IMPEY Steward Observatory, University of Arizona AND MARK SCHMITZ Department of Astronomy, The University of Michigan Received 1988 August 8; accepted 1988 November 3 ABSTRACT We present the results of extensive CCD imaging and spectroscopic and IRAS observations of the Wasilewski sample of emission-line galaxies (ELGs), which have been selected from wide-dispersion objective prism pl ates. Our motivation for these observations is (1) to examine the nature of galaxies that are preferentially found in such surveys, (2) to understand the degree to which these galaxies constitute the optically selected parent population of IRAS-detected galaxies, and (3) to determine the efficiency of selecting Seyfert galaxies by optical techniques relative to the efficiency of selecting them by far-infrared observations. With regard to these three points our basic results are as follows: (1) Selection by objective prism surveys produces an extremely heterogeneous population of galaxies. In rough terms, about 25% of the sample are members of strongly interacting systems, 25% are compact, extragalactic H II regions, which often have diameters <= 2 kpc, and 50% are late-type spirals, often with disturbed morphologies; (2) These galaxies constitute, at most, 30% of the total space density of moderate-luminosity IRAS sources and in no way can account for the most luminous IRAS sources. The contribution of these optically selected ELGs rises by at least a factor of 2 when one considers only IRAS sources that have f_60/f_100_ >= 0.5. (3) The presence of 25 micron emission, at luminosities >= 10^9^ L_sun_, provides a good initial indication of Seyfert activity. However, in the case of Seyfert 2's, there is not a particularly well-defined region in the {alpha}(25,60), {alpha}(60,100) diagram where these galaxies are well removed from other sources. Thus, both optical and far-infrared selection is necessary in order to derive the true space density of Seyert galaxies. Subject headings.: galaxies: interactions - galaxies: Seyfert - infrared: sources - nebulae: H II regions
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