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Astron. Astrophys. 355, 915-921 (2000)

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Precession, beaming and the periodic light curve of OJ287

Z. Abraham

Instituto Astronômico e Geofísico, Universidade de São Paulo, São Paulo, Brazil

Received 29 November 1999 / Accepted 17 January 2000


The strong periodic optical flares of OJ287 are explained in terms of the increase in the beaming factor when a precessing jet approaches the line of sight. The geometrical parameters of the precession are determined from the kinematical properties of the parsec scale superluminal features in the radio jet. The possible values of the Lorentz factor [FORMULA] for the bulk motion in the jet are constrained by the half-life of the optical flares. A moderate value, [FORMULA], gives the best fitting to the data.

Key words: galaxies: BL Lacertae objects: individual: OJ287 – galaxies: jets – radio continuum: galaxies – galaxies: magnetic fields – galaxies: photometry

Send offprint requests to: Z. Abraham

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© European Southern Observatory (ESO) 2000

Online publication: March 21, 2000