The EBLM project

Abstract

This paper introduces a series of papers aiming to study the dozens of low-mass eclipsing binaries (EBLM), with F, G, K primaries, that have been discovered in the course of the WASP survey. Our objects are mostly single-line binaries whose eclipses have been detected by WASP and were initially followed up as potential planetary transit candidates. These have bright primaries, which facilitates spectroscopic observations during transit and allows the study of the spin-orbit distribution of F, G, K+M eclipsing binaries through the Rossiter-McLaughlin effect. Here we report on the spin-orbit angle of WASP-30b, a transiting brown dwarf, and improve its orbital parameters. We also present the mass, radius, spin-orbit angle and orbital parameters of a new eclipsing binary, J1219-39b (1SWAPJ121921.03-395125.6, TYC 7760-484-1), which, with a mass of 95±2 M jup , is close to the limit between brown dwarfs and stars. We find that both objects have projected spin-orbit angles aligned with their primaries' rotation. Neither primaries are synchronous. J1219-39b has a modestly eccentric orbit and is in agreement with the theoretical mass-radius relationship, whereas WASP-30b lies above it.

SOPHIE velocimetry ofKeplertransit candidates

“…Indeed, an analysis of the pipeline-corrected PDC Kepler light curve yields a rotational period of around 41 days, in agreement with the spectroscopic v sin i * value. Although KOI-205 b is the smallest BD detected as yet, its bulk density is similar to that of WASP-30 b (Triaud et al 2013;Anderson et al 2011) and lower than that of LHC6343C (Johnson et al 2011). …”

“…The light curve contamination of Season 2 is around 6%. Triaud et al 2013;Bouchy et al 2011b,a;Johnson et al 2011;Hellier et al 2009;Deleuil et al 2008;Winn et al 2008;Pont et al 2005Pont et al , 2006 …”

CoRoT 101186644: A transiting low-mass dense M-dwarf on an eccentric 20.7-day period orbit around a late F-star

“…In particular, it has been claimed that the stellar radii computed from models in this mass domain are 5−15% lower than observed (e.g., López-Morales & Ribas 2005;Morales et al 2010;Kraus et al 2011). This argument is sometimes called the M-dwarf radius problem (e.g., Triaud et al 2013), and it dates back to the precise masses and radii measurements of both components of CM Draconis (Lacy 1977). However, in the domain of very low-mass stars (VLMS, M 0.2 M ), only a few studies have been published (e.g., López-Morales 2007; Boyajian et al 2012), since only a handful of precise masses and radii have been derived in this domain.…”

“…Eclipsing binaries (EBs) with low mass ratios, like M dwarfs that eclipse A-K dwarfs, draw particular attention (e.g., Bentley et al 2009;Triaud et al 2013). The high-quality photometric and spectroscopic data produced for these systems by photometric surveys like HAT (Bakos et al 2004), WASP (Pollacco et al 2006), CoRoT, Kepler (Borucki et al 2010), and their follow-up programs, allow for precise determination of physical properties, such as the masses and the radii of both components.…”

SOPHIE velocimetry ofKeplertransit candidates

“…Above 20 M Jup , only eight such objects are known: CoRoT-3 b (Deleuil et al, 2008), KELT-1 b (Siverd et al, 2012), KOI-205 b (Díaz et al, 2013), the young pair of eclipsing brown dwarfs 2M0535-05 (Stassun et al, 2007), WASP-30 b (Triaud et al, 2013), LHS 6343 C (Johnson et al, 2011), and CoRoT-15 b (Bouchy et al, 2011). The precise measurement of their mass and radius offers important constraints for the transition region between giant planets and low-mass stars, to be compared with theoretical predictions as given by, for instance, Burrows et al (1997), Chabrier et al (2000) and Baraffe et al (2003).…”