VSOP imaging of S5 0836+710: a close-up on plasma instabilities in the jet

. The luminous high-redshift ( z = 2 . 17) quasar S5 0836+710 has been observed at 5 GHz with the VSOP. We compare the properties of three images obtained from the observation: a low-resolution ground array image (dynamic range 4600:1), a full-resolution VSOP image (900:1), and an image made with only the space baselines (200:1). The space baselines alone are sufficient for a reliable recovery of the source structure, within the lim-its of the achieved spatial sampling of the visibility data. The curved jet ridge line observed in the images can be described by Kelvin-Helmholtz instabilities developing in a relativistic outflow with the Mach number of about 6. This description holds on the scales of < ∼ 700 h − 1 pc, and is shown to be consistent with variable apparent speeds observed in the jet.