Related papers: The Formation of Close Binary Systems by Dynamical…
Solar-type binaries with short orbital periods ($P_{\rm close}$ $\equiv$ 1 - 10 days; $a$ $\lesssim$ 0.1 AU) cannot form directly via fragmentation of molecular clouds or protostellar disks, yet their component masses are highly correlated,…
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…
Binary systems are very common among field stars. While this relatively small number of planets in binaries is probably partly due to strong observational biases, there is, however, statistical evidence that planets are indeed less frequent…
Combining numerical simulations and analytical modeling, we investigate whether close binary systems form by the effect of magnetic braking. Using magnetohydrodynamics simulations, we calculate the cloud evolution with a sink, for which we…
We present results from the first hydrodynamical star formation calculation to demonstrate that brown dwarfs are a natural and frequent product of the collapse and fragmentation of a turbulent molecular cloud. The brown dwarfs form via the…
Massive stars are often found in multiple systems, yet how binary-star systems with very close separations ($\lesssim$ au) assemble remains unresolved. We investigate the formation and inward migration of massive-star binaries in…
Wide gravitationally bound pairs of stars can be formed from adjacent prestellar cores that happen to move slowly enough relative to each other. These binaries are remnants of the primordial clustering. It is shown that the expected…
The orbital separation of compact binary stars will shrink with time due to the emission of gravitational radiation. This inspiralling phase of a binary system's evolution generally will be very long compared to the system's orbital period,…
The formation of massive stars is one of the major unsolved problems in stellar astrophysics. However, only few if any of these are found as single stars, on average massive stars have more than one companion. Many of them are born in dense…
The presence of highly eccentric extrasolar planets in binary stellar systems suggests that the Kozai effect has played an important role in shaping their dynamical architectures. However, the formation of planets in inclined binary systems…
We investigate the problem of structures formation in accretion disc zone, resulting from the tidally interaction in close binary star system. We aim to examine the area where the incoming flow meets the matter around secondary star and the…
I suggest a spiral-in process by which a stellar companion graze the envelope of a giant star while both the orbital separation and the giant radius shrink simultaneously, and a close binary system is formed. The binary system might be…
Dozens of planets and brown dwarfs are known to orbit one component of tight stellar binaries ($a_{\rm bin} \lesssim 20$ au), despite circumstellar discs in such systems being truncated to radii of only $\sim (0.2-5)$ au. This presents a…
Many recent observational studies have concluded that planetary systems commonly exist in multiple-star systems. At least ~20%, and presumably a larger fraction of the known extrasolar planetary systems are associated with one or more…
In contrast to the field, the binaries in dense stellar systems are frequently not primordial, and could be either dynamically formed or significantly altered from their primordial states. Destruction and formation of binaries occur in…
A binary star system is the most common result of the star formation process, and binary companions can disrupt both the formation of terrestrial planets and their long term prospects for stability. We present results from a large set of…
We present radiation hydrodynamic simulations in which binary planets form by close encounters in a system of several super-Earth embryos. The embryos are embedded in a protoplanetary disk consisting of gas and pebbles and evolve in a…
Joint statistics of periods and mass ratios of close binaries and its dependence on primary mass can be explained by assuming that seed binary companions are formed by disc fragmentation at random intervals during assemblage of stellar mass…
Some short-period, detached binary systems have recently been reported to experience very rapid orbital decay, much faster than is expected from the angular-momentum loss caused by gravitational radiation alone. As these systems contain…
Surveys of the binary populations in the solar neighbourhood have shown that the periods of G- and M-type stars are log-normally distributed. However, observations of young binary populations suggest a log-uniform distribution. Clearly some…