An eclipsing substellar binary in a young triple system discovered by SPECULOOS

Abstract

corresponding authors Mass, radius, and age are three of the most fundamental parameters for celestial objects, enabling studies of the evolution and internal physics of stars, brown dwarfs, and planets. Brown dwarfs are hydrogen-rich objects that are unable to sustain core fusion reactions but are supported from collapse by electron degeneracy pressure [1]. As they age, brown dwarfs cool, reducing their radius and luminosity. Young exoplanets follow a similar behaviour. Brown dwarf evolutionary models are relied upon to infer the masses, radii and ages of these objects [2, 3]. Similar models are used to infer the mass and radius of directly imaged exoplanets [4]. Unfortunately, only sparse empirical mass, radius and age measurements are currently available, and the models remain mostly unvalidated. Double-line eclipsing binaries provide the most direct route for the absolute determination of the masses and radii of stars [5, 6, 7]. Here, we report the SPECULOOS discovery of 2M1510A, a nearby, eclipsing, double-line brown dwarf binary, with a widely-separated tertiary brown dwarf companion. We also find that the system is a member of the 45±5 Myr-old moving group, Argus [8, 9]. The system's age matches those of currently known directly-imaged exoplanets. 2M1510A provides an opportunity to benchmark evolutionary models of brown dwarfs and young planets. We find that widely-used evolutionary models [4] do reproduce the mass, radius and age of the binary components remarkably well, but overestimate the luminosity by up to 0.65 magnitudes, which could result in underestimated photometric masses for directly-imaged exoplanets and young field brown dwarfs by 20 to 35%.

Search for (sub)stellar Companions of Exoplanet Hosts by Exploring the Second ESA-Gaia Data Release

“…i This companion was noticed by Triaud et al (2020) in the Gaia DR2 as equidistant and co-moving companion of the brown dwarf 2M 1510 A, which is listed in the EPE, consistent with our results. j KELT-23 B was first discovered by (Johns et al, 2019) with Keck/NIRC2 AO imaging, who used Gaia DR2 astrometry to prove the equidistance and common proper motion of the companion with the exoplanet host star KELT-23 A, as done in this study.…”

An eclipsing M-dwarf close to the hydrogen burning limit from NGTS

“…The 10-Gyr isochrone is indicated by the black dashed line, and NGTS J0930-18 B by the red triangle. Similar M-dwarfs fromParsons et al 2018, Triaud et al 2020and Mireles et al 2020 are shown in Black.…”

TOI-811b and TOI-852b: New Transiting Brown Dwarfs with Similar Masses and Very Different Radii and Ages from the TESS Mission

“…Two years ago, we knew of only 17 transiting BDs (and 2 BDs in an eclipsing binary system discovered by Stassun et al 2006), and only 14 of those with uncertainties on their radius at less than 10%. Now, we know of 25 BDs that transit a star (and 3 additional BDs in a triple system discovered by Triaud et al 2020), and as we show in Table 6, the TESS mission has made a steady contribution to the number of known transiting BDs over the span of its primary mission. Five of six of these TESS BDs also have improved precision on the measurements of their radii thanks to improved parallaxes from Gaia DR2.…”