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★

Context. Brown-dwarfs (BD) are substellar objects with masses intermediate between planets and stars within about 13-80 M J . While isolated brown-dwarfs are most likely produced by gravitational collapse in molecular clouds down to masses of a few M J , a nonnegligible fraction of low-mass companions might be formed through the planet formation channel in protoplanetary disks. The upper mass limit of objects formed within disks is still observationnally unknown, the main reason being the strong dearth of BD companions at orbital periods shorter than 10 years, a.k.a. the brown-dwarf desert. Aims. We aim at determining the best statistics of secondary companions within the 10-100 M Jup range within ∼10 au from the primary star, while minimising observational bias. This can help determining the mass limit separating planet-formed from star-formed browndwarfs. Moreover, the exact shape of the BD desert in a mass-period space is still underdetermined, and can strongly constrain the companion-star interactions mechanisms at work in close binary systems at small mass ratio. Methods. We made an extensive use of the radial velocity (RV) surveys of FGK stars below 60 pc distance to the Sun and in the northern hemisphere performed with the SOPHIE spectrograph at Observatoire de Haute-Provence. We derived the Keplerian solutions of the RV variations of 54 sources. Public astrometric data of the Hipparcos and Gaia missions allowed deriving direct astrometric solution of orbital motion and constraining the mass of the companion for most sources. We introduce GASTON, a new method to derive inclination combining RVs Keplerian and astrometric excess noise from Gaia DR1. Results. We report the discovery of 12 new BD candidates. For 5 of them, additional astrometric data led to revise their mass in the M-dwarf regime. Among the 7 remaining objects, 4 are confirmed BD companions, and 3 others are likely also in this mass regime. Moreover, we report the detection of 42 objects in the M-dwarf mass regime 90 M J -0.52 M . The resulting M sin i-P distribution of BD candidates shows a clear drop in the detection rate below 80-day orbital period. Above that limit, the BD desert reveals rather wet, with a uniform distribution of the M sin i. We derive a minimum BD-detection frequency around Solar-like stars of 2.0±0.5%.

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“…The mass ratio q can be found by solving the equation of the mass function (see e.g. Halbwachs et al 2014)…”

Section: Appendix A: Photocenter Semi-major Axismentioning

confidence: 99%

Detection and characterisation of 54 massive companions with the SOPHIE spectrograph

Kiefer

Hébrard

Sahlmann

et al. 2019

A&A

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“…The studies by Pourbaix and Jorissen (2000), Pourbaix and Boffin (2003), Jancart et al (2005) and Escorza et al (2019) combined spectroscopic orbital solutions with Hipparcos astrometric data to determine the mass of the unseen components in single-lined spectroscopic binary systems. To prepare the exploitation of Gaia, a long-term observational programme with the SOPHIE spectrograph at the Haute-Provence Observatory has been conducted by Halbwachs et al (2014Halbwachs et al ( , 2016, Kiefer et al (2016Kiefer et al ( , 2018 and Halbwachs et al (2020). About 70 double-lined spectroscopic binaries (some of them previously known only as single-line binaries) and also observed by Gaia (for most of them) were selected.…”

Section: Mass Estimation Of Non-eclipsing Spectroscopic Binariesmentioning

confidence: 99%

Weighing stars from birth to death: mass determination methods across the HRD

Serenelli

Weiß

Aerts

et al. 2021

Astron Astrophys Rev

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The mass of a star is the most fundamental parameter for its structure, evolution, and final fate. It is particularly important for any kind of stellar archaeology and characterization of exoplanets. There exist a variety of methods in astronomy to estimate or determine it. In this review we present a significant number of such methods, beginning with the most direct and model-independent approach using detached eclipsing binaries. We then move to more indirect and model-dependent methods, such as the quite commonly used isochrone or stellar track fitting. The arrival of quantitative asteroseismology has opened a completely new approach to determine stellar masses and to complement and improve the accuracy of other methods. We include methods for different evolutionary stages, from the pre-main sequence to evolved (super)giants and final remnants. For all methods uncertainties and restrictions will be discussed. We provide lists of altogether more than 200 benchmark stars with relative mass accuracies between ½0:3; 2% for the covered mass range of M 2 ½0:1; 16 M , 75% of which are stars burning hydrogen in their core and the other 25% covering all other evolved stages. We close with a recommendation how to combine various methods to arrive at a ''mass-ladder'' for stars.

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“…Halbwachs et al 5 presented the selection of a sample of double-lined spectroscopic binaries (SB2) for which they are obtaining precise radial velocities, with the final aim to derive at the 1% level or better the masses of the components once the Gaia astrometric measurements will be available. However, based on the reduction of the Hipparcos satellite, it is known that large space astrometric surveys may be prone to systematic errors.…”

Section: Precise Stellar Massesmentioning

confidence: 99%

An interferometric view of binary stars

Boffin

2016

SPIE Proceedings

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The study of binary stars is critical to apprehend many of the most interesting classes of stars. Moreover, quite often, the study of stars in binary systems is our only mean to constrain stellar properties, such as masses and radii. Unfortunately, a great fraction of the most interesting binaries are so compact that they can only be apprehended by high-resolution techniques, mostly by interferometry. I present some results highlighting the use of interferometry in the study of binary stars, from finding companions and deriving orbits, determining the mass and radius of stars, to studying mass transfer in symbiotic stars, and tackling luminous blue variables. In particular, I show how interferometric studies using the PIONIER instrument have allowed us to confirm a dichotomy within symbiotic stars, obtain masses of stars with a precision better than 1%, and help us find a new η Carinae-like system. I will also illustrate the benefits for the study of binary stars one would get from upgrading the VLT Interferometer so as to be able to observe in the visible range.

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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★

Cited by 13 publications

References 27 publications

Detection and characterisation of 54 massive companions with the SOPHIE spectrograph

Detection and characterisation of 54 massive companions with the SOPHIE spectrograph

Weighing stars from birth to death: mass determination methods across the HRD

An interferometric view of binary stars

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