Left panel: Stokes Q image of HP Cha. The angle of linear polarization in the Stokes Q pattern of the rim corresponds to an illumination source located at the position of the BC companions (as delineated by the butterfly shadow centered at the companions). Central panel: Smoothed PI image where we identified the rim in the circumprimary disk, the streamer connecting the circumprimary and circumsecondary disk, and the nebulous envelope surrounding the BC components. The blue bar delineates the disk height at the most extended point of the outer rim. Right panel: Overlay of ALMA CO gas emission (red contour) at the radial velocity of ~6.0 km s⁻¹. The contours delineate the flux level of [3, 5, 10, 50]σ, where σ is the standard deviation as measured in the image background. The gray ellipse denotes the beam (0.77″× 0.40″) of the ALMA observations.