2017/07/24 by A. H. M. J. Triaud, Amaury H. M. J. Triaud, David V. Martin +30 · 98 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Binary star #Circular orbit #Exoplanet #Orbit (dynamics) #Orbital period #Physics #Planet #Primary (astronomy) #RADIUS #Radial velocity #Spectral line #Spectrograph #Stars #Stellar, planetary, and galactic studies #Transit (satellite) #astro-ph.EP #astro-ph.SR
paper · pdf · doi:10.1051/0004-6361/201730993
published in Astronomy and Astrophysics 608, A129 (EDP Sciences) · 14 pages, 12 figures, 7 Tables. Under review at A&A, corrections after comments by the referee
arxiv created 2017/07/24 · openalex publication_date 2017/08/25 · arxiv updated 2017/12/20 · openalex created_date 2022/10/04 · openalex updated_date 2026/08/05
We present 2271 radial velocity measurements taken on 118 single-line binary stars, taken over eight years with the CORALIE spectrograph. The binaries consist of F/G/K primaries and M dwarf secondaries. They were initially discovered photometrically by the WASP planet survey, as their shallow eclipses mimic a hot Jupiter transit. The observations we present permit a precise characterisation of the binary orbital elements and mass function. With modelling of the primary star, this mass function is converted to a mass of the secondary star. In the future, this spectroscopic work will be combined with precise photometric eclipses to draw an empirical mass/radius relation for the bottom of the mass sequence. This has applications in both stellar astrophysics and the growing number of exoplanet surveys around M dwarfs. In particular, we have discovered 34 systems with a secondary mass below 0.2 M⊙, and so we will ultimately double the number of known very low-mass stars with well-characterised masses and radii. The quality of our data combined with the amplitude of the Doppler variations mean that we are able to detect eccentricities as small as 0.001 and orbital periods to sub-second precision. Our sample can revisit some earlier work on the tidal evolution of close binaries, extending it to low mass ratios. We find some exceptional binary systems that are eccentric at orbital periods below three days, while our longest circular orbit has a period of 10.4 days. Amongst our systems, we note one remarkable architecture in J1146-42 that boasts three stars within one astronomical unit. By collating the EBLM binaries with published WASP planets and brown dwarfs, we derive a mass spectrum with twice the resolution of previous work. We compare the WASP/EBLM sample of tightly bound orbits with work in the literature on more distant companions up to 10 AU. We note that the brown dwarf desert appears wider, as it carves into the planetary domain for our short-period orbits. This would mean that a significantly reduced abundance of planets begins at ~ 3 MJup, well before the deuterium-burning limit. This may shed light on the formation and migration history of massive gas giants.