Orbit determination for the binary Cepheid V1344 Aql

Abstract

Context. Binary Cepheids play an important role in the investigation of the calibration of the classical Cepheid period-luminosity relationship. Therefore, a thorough study of individual Cepheids belonging to binary systems is necessary. Aims. Our aim is to determine the orbit of the binary system V1344 Aql using newly observed and earlier published spectroscopic and photometric data. Methods. We collected new radial velocity observations using medium resolution (R ≈ 11 000 and R ⪅ 20 000) spectrographs, and we updated the pulsation period of the Cepheid based on available photometric observations using an O − C diagram. Separating the pulsational and orbital radial velocity variations for each observational season (year), we determined the orbital solution for the system using χ2 minimisation. Results. The updated pulsation period of the Cepheid estimated for the epoch of HJD 2458955.83 is 7.476826 days. We determined orbital elements for the first time in the literature. The orbital period of the system is about 34.6 yr, with an eccentricity of e = 0.22.