Research Note

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

¹ Astronomický ústav, Akademie věd České republiky, 251 65 Ondřejov, Czech Republic
e-mail: kubat@sunstel.asu.cas.cz
² Matematički Institut SANU, Kneza Mihaila 36, 11001 Beograd, Serbia
³ Ústav teoretické fyziky a astrofyziky PřF MU, Kotlářská 2, 611 37 Brno, Czech Republic
⁴ Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko Shossee Blvd., 1784 Sofia, Bulgaria

Received: 26 April 2015
Accepted: 3 December 2015

Abstract

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 1  Del, 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 Ondřejov Observatory. Spectra of 1  Del were successfully resolved, and, for the first time, spectra of 1  Del B were obtained. We found that 1  Del A is a Be/shell star, while 1  Del B is not an emission-line object.