Related papers: Age Determination in Upper Scorpius with Eclipsing…
Various surveys of low-mass binaries in star forming regions have been performed in recent years. They reached opposite conclusions concerning possible binary excesses in some of these associations. I develop a consistent method to…
The solar galactic neighbourhood contains a number of young co-moving associations of stars (so-called `young moving groups') with ages of ~10--150 Myr, which are prime targets for a range of scientific studies, including direct imaging…
BEBOP-3 is detached eclipsing binary star that shows total eclipses of a faint M~dwarf every 13.2 days by a 9$^{\rm th}$-magnitude F9V star. High precision radial velocity measurements have recently shown that this binary star is orbited by…
We present the most comprehensive analysis to date of the Upper Centaurus Lupus eclipsing binary MML 53 (2.097892 d), and for the first time, confirm the bound-nature of the third star (~9yr orbit). Our analysis uses new and archival…
The early-type massive binary MQ Cen (P$_{orb}$=3.7 d) has been investigated by means of high-resolution ($R\sim48\,000$) spectral analysis and multi-band (Johnson $BVRI$ and Str\"{o}mgren $vby$) light curve modeling. The physical…
Free-floating planetary-mass objects (FFPs) have been detected through direct imaging in several young, nearby star-forming regions. The properties of circumstellar disks around these objects may provide a valuable probe into their origin…
We present photometric, astrometric, and spectroscopic observations of USco160611.9-193532 AB, a candidate ultrawide (~1600 AU), low-mass (M_tot~0.4 M_sun) multiple system in the nearby OB association Upper Scorpius. We conclude that both…
Context: A rich population of low-mass brown dwarfs and isolated planetary mass objects has been reported recently in the Upper Scorpius and Ophiuchus star forming complex. Aims: We investigate the membership, nature and properties of 17 of…
We observed stars with variable radial velocities to determine their spectroscopic orbits. Velocities of 132 targets taken over a time span reaching 30 years are presented. They were measured with the correlation radial velocity…
We present the characterization of CRTS J055255.7$-$004426 (=THOR 42), a young eclipsing binary comprising two pre-main sequence M dwarfs (combined spectral type M3.5). This nearby (103 pc), short-period (0.859 d) system was recently…
We use several main-sequence models to derive distances (and extinctions), with statistically meaningful uncertainties for 11 star-forming-regions and young clusters. The model dependency is shown to be small, allowing us to adopt the…
We present the discovery of a planetary-mass companion to CFHTWIR-Oph 98, a low-mass brown dwarf member of the young Ophiuchus star-forming region, with a wide 200-au separation (1.46 arcsec). The companion was identified using Hubble Space…
Intermediate resolution (R=7000) spectroscopy is presented for 76 photometrically selected very low mass (0.04<M<0.3M_{sun}) candidate members of the Sigma Orionis cluster. More than two thirds appear to be genuine cluster members on the…
Planet formation theories predict a large but still undetected population of short-period terrestrial planets orbiting brown dwarfs. Should specimens of this population be discovered transiting relatively bright and nearby brown dwarfs, the…
We identify 231 objects in the newly released Cycle 0 dataset from the Kepler Mission as double-eclipse, detached eclipsing binary systems with Teff < 5500 K and orbital periods shorter than ~32 days. We model each light curve using the…
Low-mass eclipsing binaries show systematically larger radii than model predictions for their mass, metallicity and age. Prominent explanations for the inflation involve enhanced magnetic fields generated by rapid rotation of the star that…
Long-period brown dwarf companions detected in radial velocity surveys are important targets for direct imaging and astrometry to calibrate the mass-luminosity relation of substellar objects. Through a 20-year radial velocity monitoring of…
We present the first modern analysis of two young, eclipsing binaries, EK Cep and HS Her, based on new, ground-based, CCD multicolour light curves as well as the TESS observations, radial velocity curves, and eclipse timing measurements.…
One of the most effective ways to test stellar evolutionary models is to measure dynamical masses for binary systems at a range of temperatures. In this paper, we present orbits of three young K+M binary systems in Taurus (Hubble~4, FF~Tau,…
The masses and temperatures of young low mass stars and brown dwarfs in star- forming regions are not yet well established because of uncertainties in the age of individual objects and the spectral type vs. temperature scale appropriate for…