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Astron. Astrophys. 325, 484-492 (1997)

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The parsec-scale evolution of the superluminal quasar 1642+690

T. Venturi 1, 2, T.J. Pearson 2, P.D. Barthel 3 and S.C. Unwin 2, 4

1 Istituto di Radioastronomia del CNR, Via Gobetti 101, I-40129, Bologna, Italy
2 California Institute of Technology, 105-24, Pasadena, CA 91125, USA
3 Kapteyn Astronomical Institute, P. O. Box 800, AV Groningen, The Netherlands
4 Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA

Received 24 February 1997 / Accepted 21 March 1997

Abstract

We present the results of a 6 cm VLBI monitoring program of the core dominated, radio loud quasar 1642+690. 3.6 cm VLBI observations are also presented. The 6 cm observations, carried out in 1986.4, 1988.2, 1992.2 and 1994.7 confirm that the source is variable, both in morphology and in flux density, its changes reflecting a complicated evolution.

We propose a few evolutionary scenarios, and favour the interpretation of the superluminal character of 1642+690, with a flow of superluminal components ejected from the core at a very similar high apparent speed, [FORMULA], in agreement with the first claim of superluminal motion in this source.

Key words: galaxies: active – quasars: general – radio continuum: galaxies – quasars: Q1642+690

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© European Southern Observatory (ESO) 1997

Online publication: April 28, 1998

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