In situ solar wind plasma parameters observed by STEREO-B. From top to bottom: proton density, proton bulk velocity, proton temperature and expected temperature (red dashed), pitch angle distribution of ∼272 eV suprathermal electrons, magnitude of magnetic field, components of the magnetic field in RTN coordinates, magnetic field azimuthal angle (225°; dashed horizontal line), alpha-to-proton number ratio. The solid vertical line indicates the stream interface. The dashed line indicates the shock in front of the CIR. The pink shading shows the very low density region.