Bright Spectroscopic Binaries: I. Orbital parameters of five systems with periods of P < 365 days

TL;DR

This study reports the discovery and orbital analysis of five bright spectroscopic binary stars with periods less than a year, using Gaia DR2 data and the TIGRE telescope, providing detailed stellar and orbital parameters.

Contribution

It presents the first orbital parameters for five bright spectroscopic binaries with short periods, derived from Gaia data and spectroscopic observations, including stellar and secondary mass estimates.

Findings

Orbital parameters for five short-period binaries are determined.

All primary stars are evolved giants with low-mass secondaries.

Secondary stars' minimum masses are estimated, revealing low-mass companions.

Abstract

In a well-aimed search based on the recently published Gaia~DR2 radial velocity data and performed with the robotic TIGRE telescope, we have discovered 19 bright ($m_V<7.66$~mag) spectroscopic binary stars. We present the radial velocity curves of five of these stars (HD~20656, HD~27259, HD~98812, HD~150600, HD~193082) with periods of $P<365$~days. We determined their orbital parameters using the toolkit RadVel. The complete set of basic stellar parameters (effective temperature, surface gravity, metallicity, mass and age) of the primary stars are determined using the observed intermediate resolution spectra ($R\approx20,000$) with iSpec and a comparison of the position in the HRD with stellar evolution tracks. All five primary stars have already evolved to the giant phase and possess low-mass secondaries, which do not noticeably affect the spectra. Finally, we determined the minimum masses of the secondary stars of the binary systems and present conclusions about the properties of the binary systems.