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Astron. Astrophys. 325, 484-492

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

T. Venturi1,2, T.J. Pearson2, P.D. Barthel3, and S.C. Unwin2,4

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

Received 24 February 1997 / Accepted 21 March 1997


We present the results of a 6cm VLBI monitoring program of the core dominated, radio loud quasar 1642+690. 3.6cm VLBI observations are also presented. The 6cm 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

© European Southern Observatory (ESO) 1997

Online publication: September 9, 1997
Last change: April 28, 1998