Issue |
Astron. Astrophys. Suppl. Ser.
Volume 133, Number 3, December II 1998
|
|
---|---|---|
Page(s) | 353 - 359 | |
DOI | https://doi.org/10.1051/aas:1998326 | |
Published online | 15 December 1998 |
The variable sources responsible for the photometric behaviour of OJ 287 in the IR-optical-UV region during 1993-1996
1
Astronomical Institute of St. Petersburg State University, 198904 St. Petersburg, Russia
2
Tuorla Observatory, Tuorla 21500, Piikkiö, Finland
3
Boltwood Observatory, 1655 Main St., Stittsville, Ontario, Canada
4
Instituto de Astrofisica de Canarias, La Laguna, 38200 Tenerife, Spain
Received:
20
October
1997
Accepted:
22
June
1998
An analysis is performed of multicolour observations of OJ 287
carried out during the OJ-94 Project. It is found that in
the optical region the variable sources have the same power-law spectrum
irrespective of flux level. In the IR
the spectrum flattens during the flare possibly because of
synchrotron self-absorption. The comparison of the outburst of
1994 with those of 1971 and 1983 shows that there is a clear
correlation between the power of outburst and colour indices
of the variable component in each event: the larger is the
outburst, the bluer is the variable source, i.e. in more
powerful outbursts the energy spectrum of relativistic electrons
is flatter.
Key words: BL Lac objects; OJ 287 / infrared: galaxies
© European Southern Observatory (ESO), 1998