The hierarchical triple system DY Lyncis

Abstract

We present the results of a six-year spectroscopic monitoring of DY Lyncis. Three different echelle spectrographs were used to collect the spectroscopic data. Each DY Lyncis spectrum contains lines of three different stars. Two of them belong to a very close eclipsing binary (EB) with an orbital period of 1.3 d. The reflex motion due to the third body can be observed in the radial velocities of the EB. We found the period of the wide orbit to be 281 d and its eccentricity is 0.33. We used the Wilson-Devinney method to fit both orbits. The analysis revealed that the EB consists of two very similar stars of 1.21 and 1.14 M_⊙, corresponding to a mass ratio of 0.94. The fit of the long-period orbit showed that the third body is the most massive component in the system, its mass is 1.40 M_⊙. Additionally, the atmospheric parameters were calculated for all three components. For that, we acquired spectra with a 2-m class telescope where we obtained sufficient signal-to-noise ratio. We derived temperatures of 6370 ± 150 and 6260 ± 140 K for the EB components, and 6380 ± 110 K for the most massive star. From the combined photometric and spectroscopic analysis, we estimate that the distance and age of the system are 285 pc and 2.5 Gyr, respectively.