Free Access

Fig. 1


Geometry of the precession model (not to scale) adopted from Qian (2011). The Z-axis, which is taken to be the axis of precession, is defined by parameters (ϵ, ψ); the Yp axis indicates the direction toward the observer; the position of a knot (superluminal component) is defined by parameters (A,Φ); A(Z) is the amplitude function and Φ is the azimuthal angle (or phase); the plane (Xp,Zp) represents the plane of the sky; and θ denotes the angle between the knot’s velocity vector (S) and the direction toward the observer (V). η is the initial half opening angle of the precessing jet cone (see text).

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.