The inner environment of Z Canis Majoris: High-contrast imaging polarimetry with NaCo

Context. Z CMa is a binary composed of an embedded Herbig Be and an FU Ori class star separated by similar to 100 au. Observational evidence indicates a complex environment in which each star has a circumstellar disk and drives a jet, and the whole system is embedded in a large dusty envelope. Aims. We aim to probe the circumbinary environment of Z CMa in the inner 400 au in scattered light. Methods. We use high-contrast imaging polarimetry with VLT/NaCo at the H and K-s bands. Results. The central binary is resolved in both bands. The polarized images show three bright and complex structures: a common dust envelope, a sharp extended feature previously reported in direct light, and an intriguing bright clump located 0 ''.3 south of the binary, which appears spatially connected to the sharp extended feature. Conclusions. We detect orbital motion when compared to previous observations, and report a new outburst driven by the Herbig star. Our observations reveal the complex inner environment of Z CMa in unprecedented detail and contrast.