Spectroscopy of close visual binary components of the stable shell star 1Delphini

Stable shell stars are ideal objects for studying basic physical principles of the formation of disks in Be stars. If these stars have a close unresolved visual companion, its contribution toward the modelling of the disk cannot be overlooked, as is sometimes done. The study aims to spectroscopically resolve close visual binary Be (shell) star 1Del, which up to now was only resolved by speckle or micrometric measurements. The integral field spectroscopy obtained by the SINFONI spectrograph at the VLT telescope in the European Southern Observatory (ESO) in the infrared region was used; we supplemented these observations with visual spectroscopy with the Perek Telescope at the Ondrejov Observatory. Spectra of 1Del were successfully resolved, and, for the first time, spectra of 1DelB were obtained. We found that 1DelA is a Be/shell star, while 1DelB is not an emission-line object.