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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
Abstract
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]](img1.gif)
for the bulk motion in
the jet are constrained by the half-life of the optical flares. A
moderate value, ![[FORMULA]](img2.gif)
, 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
© European Southern Observatory (ESO) 2000
Online publication: March 21, 2000
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