Related papers: The minimum mass for star formation, and the origi…
We investigate the formation of brown dwarfs and very low-mass stars through the gravitational fragmentation of infalling gas into stellar clusters. The gravitational potential of a forming stellar cluster provides the focus that attracts…
A complete accounting of nearby objects -- from the highest-mass white dwarf progenitors down to low-mass brown dwarfs -- is now possible, thanks to an almost complete set of trigonometric parallax determinations from Gaia, ground-based…
Recent studies have shown that close-in brown dwarfs in the mass range 35-55 M$_{\rm Jup}$ are almost depleted as companions to stars, suggesting that objects with masses above and below this gap might have different formation mechanisms.…
Recent observations of binary stars in the Galactic field show that the binary fraction and the mean orbital separation both decrease as a function of decreasing primary mass. We present $N$-body simulations of the effects of dynamical…
Brown dwarfs and very low mass stars are a significant fraction of stars in our galaxy, and they are interesting laboratories to investigate planet formation in extreme conditions of low temperature and densities. In addition, the dust…
We rehearse the physical and theoretical considerations that define the nature of Brown Dwarfs, in particular the maximum mass for a Brown Dwarf (set by the Hydrogen-Burning Limit) and the minimum mass for a Brown Dwarf (set by the Opacity…
We explore the possibility that, in the vicinity of an OB star, a prestellar core which would otherwise have formed an intermediate or low-mass star may form a free-floating brown dwarf or planetary-mass object, because the outer layers of…
Although many models have been proposed, the physical mechanisms responsible for the formation of low-mass brown dwarfs are poorly understood. The multiplicity properties and minimum mass of the brown-dwarf mass function provide critical…
Direct imaging searches have revealed many very low-mass objects, including a small number of planetary mass objects, as wide-orbit companions to young stars. The formation mechanism of these objects remains uncertain. In this paper we…
Context: We studied numerically the formation of giant planet (GP) and brown dwarf (BD) embryos in gravitationally unstable protostellar disks and compared our findings with directly-imaged, wide-orbit (>= 50 AU) companions known to-date.…
We review the statistical properties of stars and brown dwarfs obtained from the first hydrodynamical simulation of star cluster formation to produce more than a thousand stars and brown dwarfs while simultaneously resolving the lowest mass…
The mass domain where massive extrasolar planets and brown dwarfs overlap is still poorly understood due to the paucity of brown dwarfs orbiting close to solar-type stars, the so-called brown dwarf desert. In this paper we collect all of…
Disc fragmentation plays an important role in determining the number of primordial stars (Pop III stars), their masses, and hence the initial mass function. In this second paper of a series, we explore the effect of uniform FUV…
Context: Around 30 per cent of the observed exoplanets that orbit M dwarf stars are gas giants that are more massive than Jupiter. These planets are prime candidates for formation by disc instability. Aims: We want to determine the…
We argue that gravitational instability of typical protostellar disks is not a viable mechanism for the fragmentation into multiple systems -- binary stars, brown dwarf companions, or gas giant planets -- except at periods above roughly…
The typical product of the star formation process is a binary star. Binaries have provided the first dynamical measures of the masses of pre-main-sequence (PMS) stars, providing support for the calibrations of PMS evolutionary tracks.…
The formation of objects below or close to the hydrogen burning limit is currently vividly discussed and is one of the main open issues in the field of the origins of stars and planets. Applying various observational techniques, we explored…
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…
It is now reasonably clear that disc fragmentation can only operate in the outer parts of protostellar discs ($r > 50$ au). It is also expected that any object that forms via disc fragmentation will have an initial mass greater than that of…
I discuss the role that disc fragmentation plays in the formation of gas giant and terrestrial planets, and how this relates to the formation of brown dwarfs and low-mass stars, and ultimately to the process of star formation. Protostellar…