On the derivation of radial velocities of SB2 components: a "CCF vs TODCOR" comparison

The radial velocity (RV) of a single star is easily obtained from cross-correlation of the spectrum with a template, but the treatment of double-lined spectroscopic binaries (SB2s) is more difficult. Two different approaches were applied to a set of SB2s: the fit of the cross-correlation function with two normal distributions, and the cross-correlation with two templates, derived with the TODCOR code. It appears that the minimum masses obtained through the two methods are sometimes rather different, although their estimated uncertainties are roughly equal. Moreover, both methods induce a shift in the zero point of the secondary RVs, but it is less pronounced for TODCOR. All-in-all the comparison between the two methods is in favour of TODCOR.Comment: 5 pages, 4 figures, SF2A Conference 201

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

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.Comment: 8 pages, 3 figures, accepted for publication in MNRA

Astrometric binaries with a variable component

We present two models dedicated to unresolved binary systems hosting a photometric variable: the first is the 'VIM' (for Variability Induced Movers) model, which deals with couples of fixed stars. The second consists of the calculation of the astrometric orbit of the so-called 'orbital VIM' systems; in this case, the photometric variability of the system is used to derive the semi-major axis of the orbit of the variable component around the barycentre, instead of the usual photocentric orbit. Additional information about the physical properties of the system are thus obtained.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

Détection et classification des étoiles variables du programme Tycho

AIX-MARSEILLE1.OAMP.Le Verrier (130552205) / SudocLYON1 ST GENIS-Observatoire (692042202) / SudocSTRASBOURG-Sc. et Techniques (674822102) / SudocPARIS-Observatoire (751142302) / SudocMEUDON-Observatoire (920482302) / SudocBORDEAUX1-Observatoire (331672201) / SudocSudocFranceF

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 l'Observation des PHénomènes des Intérieurs stellaires et des Exoplanètes (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.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Binaries and distances

info:eu-repo/semantics/publishe

Seven SB2 masses using Hipparcos intermediate astrometric data

The spectroscopic orbital elements of seven double-lined spectroscopic binaries have been combined with the Hipparcos astrometric data. Dynamical masses and magnitude differences are determined with a precision of about 15% on average, and the astrometric parameters are improved