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For refcode 1990A&A...231..333F:
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Copyright by European Southern Observatory (ESO). Reproduced by permission
1990A&A...231..333F On the nature of compact steep spectrum radio sources R. Fanti, C. Fanti, R.T. Schilizzi, R.E. Spencer, Nan Rendong, P. Parma, W.J.M. van Breugel and T. Venturi Dipartimento di Astronomia dell'Universita, Via Zamboni 33, I-40126 Bologna, Italy Istituto di Radioastronomia Via Irnerio 46, I-40126 Bologna, Italy Netherlands, Foundation for Research in Astronomy, Radiosterrewacht Dwingeloo, Postbus 2, 7990 AA Dwingeloo, The Netherlands Nuffield Radio Astronomy Laboratories, University of Manchester, Jodrell Bank, Macclesfleld, Cheshire SK1 19L, UK Beijing Observatory, Academia Sinica, Beijing, Peoples Republic of China University of California, Radio Astronomy Laboratories, 601 Campbell Hall, Berkeley, CA 94720, USA Owens Valley Radio Observatory, California Institute of Technology, Pasadena, CA 91125, USA Received July 25, accepted September 19, 1989 Abstract. In this paper we discuss the properties of Compact Steep-spectrum radio Sources (CSS's), based on VLA, MERLIN and VLBI data. A classification based on radio morphology is presented. It is found that there is a clear distinction between the radio structure of galaxies and quasars. Galaxies generally have a simple double radio structure, sometimes with weak radio jets and weak radio cores. Quasars, on the other hand, show either a triple structure, with a strong central component, or jet-like or complex morphology. Their cores and jets are considerably stronger than in radio galaxies. On the basis of various arguments, we show that most (>~ 70%) of the CSS sources are likely to be intrinsically small (not foreshortened by projection effects) and that there is no major radio luminosity amplification by Doppler effects. On the assumption that CSS sources are an early stage of radio source evolution, we estimate, from their rate of occurrence, that this stage lasts <~ 5 10^6^ years. This is consistent with dynamical time scales calculated on the assumption of ambient gas densities of 0.1-1 cm^-3^ in the inner few kpc of the parent optical objects. Key words: radio sources - radio galaxies - quasars - jets
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