Annual Meeting of the Deep Sky Section, 2007 March 3


OJ287 – An Update

Mr Poyner explained that OJ287 was a quasar which showed variability on all timescales from minutes to years; it was widely thought, though by no means confirmed, to be a binary pair of black holes, with accretion disc viewed face-on, looking directly down its jet. In this model, its flaring behaviour was attributed to shock fronts in the jet.

It had until recently been thought to have a period of 11.5 years, though its most recent outburst, predicted for mid-2006, had occurred earlier than expected, in October/November 2005. It was now suspected that the object only showed periodic behaviour for around 50 years at a time before this became unstable, as had apparently just happened.

Being in Cancer, it was unobservable from June through September; the speaker showed a lightcurve of its behaviour since solar conjunction in 2006, up to the present. It had never been entirely quiescent in this time; initially it had appeared to flare every 31 days, though this period had recently reduced to 14 days.

The Variable Star Section had in recent times undergone a revolution; though visual observers remained, many now used CCDs to perform photometry of objects like OJ287. Noting that many of the deep sky observers in the audience also had CCD equipment, the speaker put out a call for them to consider contributing observations of this most enigmatic object. He closed by referring potential observers to the VSS's observing campaign webpage5 for more details.

The Director then invited Mr Owen Brazell to present the afternoon's final talk.




Color scheme