Benoît Famaey

Masses of the components of SB2s observed with Gaia -- II. Masses derived from PIONIER interferometric observations for Gaia validation

In anticipation of the Gaia astrometric mission, a sample of spectroscopic binaries is being observed since 2010 with the Spectrograph pour lObservation des PHenomenes des Interieurs stellaires et des Exoplanetes (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 per cent when combined with Gaia astrometric measurements. In order to validate the masses derived from Gaia, interferometric observations are obtained for three SB2s in our sample with F-K components: HIP 14157, HIP 20601 and HIP 117186. The masses of the six stellar components are derived. Due to its edge-on orientation, HIP 14157 is probably an eclipsing binary. We note that almost all the derived masses are a few per cent larger than the expectations from the standard spectral type-mass calibration and mass-luminosity relation. Our calculation also leads to accurate parallaxes for the three binaries, and the Hipparcos parallaxes are confirmed.

Masses of the components of SB2 binaries observed with Gaia – III. Accurate SB2 orbits for 10 binaries and masses of HIP 87895

In anticipation of the Gaia astrometric mission, a large sample of spectroscopic binaries has been observed since 2010 with the Spectrographe pour lObservation des PHenomenes des Interieurs Stellaires et des Exoplanetes 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 per cent when the astrometric measurements of Gaia are taken into account. In this paper, we present the results from five years of observations of 10 SB2 systems with periods ranging from 37 to 881 d. Using the todmor algorithm, we computed radial velocities from the spectra, and then derived the orbital elements of these binary systems. The minimum masses of the components are then obtained with an accuracy better than 1.2 per cent for the 10 binaries. Combining the radial velocities with existing interferometric measurements, we derived the masses of the primary and secondary components of HIP 87895 with an accuracy of 0.98 and 1.2 per cent, respectively.

Masses of the components of SB2 binaries observed with Gaia – IV. Accurate SB2 orbits for 14 binaries and masses of three binaries

ABSTRACT In anticipation of the Gaia astrometric mission, a large sample of spectroscopic bina-ries is being observed since 2010 with the Sophie spectrograph at the Haute–ProvenceObservatory. Our aim is to derive the orbital elements of double-lined spectroscopicbinaries (SB2s) with an accuracy sufficient to finally obtain the masses of the com-ponents with relative errors as small as 1 % when the astrometric measurements ofGaia are taken into account. Simultaneously, the luminosities of the components inthe Gaia photometric band Gwill also be obtained. Our observation program startedwith 200 SBs, including 152 systems that were only known as single-lined. Thanks tothe high efficiency of the Sophie spectrograph, an additional component was found for25 SBs. After rejection of 5 multiple systems, 20 new SB2s were retained, including8 binaries with evolved primary, and their mass ratios were derived. Our final samplecontains 68 SB2s, including 2 late-type giants and 10 other evolved stars.Key words: binaries: spectroscopic