Related papers: Conditions for the Formation of First-Star Binarie…
We describe how star formation is expected to proceed in the early metal-free Universe, focusing on the very first generations of stars. We then discuss how the star formation process may change as the effects of metallicity, external…
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…
Performing 1D hydrodynamical calculations coupled with non-equilibrium processes for H2 formation, we pursue the thermal and dynamical evolution of filamentary primordial clouds and attempt to make an estimate on the mass of population III…
We present numerical simulations of how a 120 M$_\odot$ primordial star regulates star formation in nearby cosmological halos at $z \sim$ 20 by photoevaporation. Our models include nine-species primordial chemistry and self-consistent…
Among many physical processes involved in star formation, radiation transfer is one of the key processes since it dominantly controls the thermodynamics. Because metallicities control opacities, they are one of the important environmental…
Recent observations of young stellar systems with the Atacama Large Millimeter/submillimeter Array (ALMA) and the Karl G. Jansky Very Large Array (VLA) are helping to cement the idea that close companion stars form via fragmentation of a…
In order to interpret the results of complex realistic star cluster simulations, which rely on many simplifying approximations and assumptions, it is essential to study the behavior of even more idealized models, which can highlight the…
We propose an evolutionary path for prestellar cores on the radius-mass diagram, which is analogous to stellar evolutionary paths on the Hertzsprung-Russell Diagram. Using James Clerk Maxwell Telescope (JCMT) observations of L1688 in the…
Massive stars influence their surroundings through radiation, winds, and supernova explosions far out of proportion to their small numbers. However, the physical processes that initiate and govern the birth of massive stars remain poorly…
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…
Core collapse is a prominent evolutionary stage of self-gravitating systems. In an idealised collisionless approximation, the region around the cluster core evolves in a self-similar way prior to the core collapse. Thus, its radial density…
Using smoothed particle hydrodynamics in combination with the special-purpose hardware device GRAPE, we follow the fragmentation process and dynamical evolution in the interior of molecular clouds until most of the gas is converted to form…
We study the circumstances under which first collisions occur in young and dense star clusters. The initial conditions for our direct $N$-body simulations are chosen such that the clusters experience core collapse within a few million…
Understanding the formation of binary and multiple stellar systems largely comes down to studying the circumstances for the fragmentation of a condensing core during the first stages of the collapse. However, the probability of…
We explore the impact of a cosmic ray (CR) background generated by supernova explosions from the first stars on star-forming metal-free gas in a minihalo at $z\sim25$. Starting from cosmological initial conditions, we use the smoothed…
Sheet-like clouds are common in turbulent gas and perhaps form via collisions between turbulent gas flows. Having examined the evolution of an isothermal shocked slab in an earlier contribution, in this work we follow the evolution of a…
Fragmentation in a gravitationally unstable accretion disk can be an important pathway for forming stellar/planetary companions. To characterize quantitatively the condition for and outcome of fragmentation under realistic thermodynamics,…
Accretion discs at sub-pc distances around supermassive black holes are likely to cool rapidly enough that self-gravity results in fragmentation. Here, we use high-resolution hydrodynamic simulations of a simplified disc model to study how…
Improving our understanding of the earliest stages of star formation is crucial to gain insight into the origin of stellar masses, multiple systems, and protoplanetary disks. We discuss recent advances made in this area thanks to detailed…
The first bound star-forming systems in the universe are predicted to form at redshifts of about 30 and to have masses of the order of 10^6 M_sun. Although their sizes and masses are similar to those of present star-forming regions, their…