Large-scale hourglass nebula of CK Vul. The background optical image shows the nebular emission in lines of Hα and [N II]. Although most stars are removed from the image, some considerable residuals can be seen (most of the point-like sources; Hajduk et al. 2007). The red dashed rectangle of 26′′ × 31′′ corresponds to the size of the maps in Fig. 11. The cyan contours show emission of CO 1–0. The dashed lines mark the symmetry axes of: the large hourglass nebula (green), the CO region (black), and the optical shell immediately surrounding the molecular nebula (magenta).