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Addendum published on 28 May 2018, see Galaxies 2018, 6(2), 59.
Open AccessArticle

OJ 287 as a Rotating Helix

Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA
Academic Editors: Jose L. Gómez, Alan P. Marscher and Svetlana G. Jorstad
Galaxies 2017, 5(1), 12;
Received: 6 September 2016 / Revised: 9 January 2017 / Accepted: 16 January 2017 / Published: 8 February 2017
(This article belongs to the Special Issue Blazars through Sharp Multi-wavelength Eyes)
We present preliminary data from high-cadence 15-GHz VLBA images of OJ 287 from 1995 to 2015. The ridgelines suggest that the jet is rotating, perhaps with a period of∼30 years. The EVPA of the core rotated by 240° in 2001–2002 and decreased slowly after that. The inner jet apparently moved to a new direction after the rotation,as shown by the emergence of a new component at a new PA at 43 GHz, in 2004. This was presaged by a strong rise in the flux density of the core, and then its sudden fall as the new component was identified. The equivalent sequence of events took place about 5 years later at 15 GHz, but in addition the core EVPA had a step in 2006 and moved to be aligned with the new 43-GHz component. The 15-GHz core became optically thin in 2006, but the angular resolution was insufficient to separate the new component from the core until 2010 View Full-Text
Keywords: BL Lacertae objects: individual (OJ 287); galaxies: active; galaxies: jets; magnetohydrodynamics (MHD); waves BL Lacertae objects: individual (OJ 287); galaxies: active; galaxies: jets; magnetohydrodynamics (MHD); waves
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Cohen, M.H. OJ 287 as a Rotating Helix. Galaxies 2017, 5, 12.

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