Masses of the components of SB2 binaries observed with Gaia. I. Selection of the sample and mass ratios of 20 new SB2s discovered with Sophie

TL;DR

This study aims to determine the masses and luminosities of components in double-lined spectroscopic binaries observed with Gaia, by analyzing a sample of 68 SB2 systems with high-precision spectroscopic data from Sophie.

Contribution

It presents the selection and analysis of 20 new SB2 binaries, enhancing the sample for future Gaia-based mass and luminosity determinations.

Findings

Discovered 20 new SB2 systems with derived mass ratios.

Expanded the sample to 68 SB2s, including evolved stars.

Identified additional components in 25 SBs from initial single-lined systems.

Abstract

In anticipation of the Gaia astrometric mission, a large sample of spectroscopic binaries is being observed since 2010 with the Sophie spectrograph at the Haute--Provence Observatory. Our aim is to derive the orbital elements of double-lined spectroscopic binaries (SB2s) with an accuracy sufficient to finally obtain the masses of the components with relative errors as small as 1% when the astrometric measurements of Gaia are taken into account. Simultaneously, the luminosities of the components in the Gaia photometric band G will also be obtained. Our observation program started with 200 SBs, including 152 systems that were only known as single-lined. Thanks to the high efficiency of the Sophie spectrograph, an additional component was found for 25 SBs. After rejection of 5 multiple systems, 20 new SB2s were retained, including 8 binaries with evolved primary, and their mass ratios were derived. Our final sample contains 68 SB2s, including 2 late-type giants and 10 other evolved stars.