Related papers: Resolving the MYSO binaries PDS 27 and PDS 37 with…

We have searched for visual binaries with projected separations in the range 200-3000 AU (0.1"-1.5") among a sample of 96 stars in the massive young NGC 6611 cluster, 60 of them being subsequently identified as high probability cluster…

We conducted a survey of nearby binary systems composed of main sequence stars of spectral types F and G in order to improve our understanding of the hierarchical nature of multiple star systems. Using Robo-AO, the first robotic adaptive…

The majority of stars in the Galactic field and halo are part of binary or multiple systems. A significant fraction of these systems have orbital separations in excess of thousands of astronomical units, and systems wider than a parsec have…

A few years ago, we investigated MYSO G29.862-0.0044 (YSO-G29), an intriguing star-forming region at a distance of 6.2 kpc. Although the typical disc-jet scenario was proposed to explain the observations, it remained far from conclusive.…

At high metallicity, a majority of massive stars have at least one close stellar companion. The evolution of such binaries is subject to strong interaction processes, heavily impacting the characteristics of their life-ending supernova and…

We present an analysis of a slightly eccentric ($e=0.05$), partially eclipsing long-period ($P = 69.73$ d) main sequence binary system (WOCS 12009, Sanders 1247) in the benchmark old open cluster M67. Using Kepler K2 and ground-based…

Almost all massive stars are part of a binary system. Given the wide range of separations at which these companions are found, several observational techniques have been adopted to characterize them, but contrasts greater than 4 in the…

We present the results of a speckle interferometric survey of Galactic massive stars that complements and expands upon a similar survey made over a decade ago. The speckle observations were made with the KPNO and CTIO 4 m telescopes and…

The surroundings of massive protostars constitute an accretion disc which has numerically been shown to be subject to fragmentation and responsible for luminous accretion-driven outbursts. Moreover, it is suspected to produce close binary…

The frequency of multiple systems and their properties are key constraints of stellar formation and evolution. Formation mechanisms of very low-mass (VLM) objects are still under considerable debate and an accurate assessment of their…

It is a challenge to study the formation process of massive stars: their formation time is short, they are few, often deeply embedded, and at relatively large distances. Our strategy is to study the outcome of the star formation process and…

The rarity of young massive stars combined with the fact that they are often deeply embedded has limited the understanding of their formation. Ground based mid-infrared (IR) interferometry is one way of securing the spatial resolution…

Almost all massive stars have bound stellar companions, existing in binaries or higher-order multiples. While binarity is theorized to be an essential feature of how massive stars form, essentially all information about such properties is…

The origin of subluminous B stars is still an unsolved problem in stellar evolution. Single star as well as close binary evolution scenarios have been invoked but until now have met with little success. We have carried out a small survey of…

We present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we conducted with the Fine Guidance Sensor 1R (FGS1r) on the Hubble Space Telescope. FGS1r is able to resolve binary systems with…

Free-floating planetary mass objects--worlds that roam interstellar space untethered to a parent star--challenge conventional notions of planetary formation and migration, but also of star and brown dwarf formation. We focus on the…

Early B-type main-sequence (MS) stars (M$_1$ = 5-16 M$_{\odot}$) with closely orbiting low-mass stellar companions (q = M$_2$/M$_1$ < 0.25) can evolve to produce Type Ia supernovae, low-mass X-ray binaries, and millisecond pulsars. However,…

Massive young stellar objects (MYSO) are surrounded by massive dusty envelopes. Our aim is to establish their density structure on scales of ~1000 AU, i.e. a factor 10 increase in angular resolution compared to similar studies performed in…

We study the formation of massive Population III binary stars using a newly developed radiation hydrodynamics code with the adaptive mesh refinement and adaptive ray-tracing methods. We follow the evolution of a typical primordial…

The formation of stars above about twenty solar masses and their apparently high multiplicity remain heavily debated subjects in astrophysics. We have performed a vast high-resolution radial velocity spectroscopic survey of about 250 O- and…