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

Abstract

Context. Z CMa is a binary composed of an embedded Herbig Be and an FU Ori class star separated by ∼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 Ks 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. 003 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.