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We employ the three-dimensional magnetohydrodynamic simulation including ambipolar diffusion to study the gravitationally-driven fragmentation of subcritical molecular clouds, in which the gravitational fragmentation is stabilized as long…

Solar and Stellar Astrophysics · Physics 2015-05-20 Takahiro Kudoh , Shantanu Basu

We investigate protostellar collapse of molecular cloud cores by numerical simulations, taking into account turbulence and magnetic fields. By using the adaptive mesh refinement technique, the collapse is followed over a wide dynamic range…

Solar and Stellar Astrophysics · Physics 2015-05-19 Tomoaki Matsumoto , Tomoyuki Hanawa

We present numerical investigations into the formation of massive stars from centrally condensed turbulent cores. The results of five hydrodynamical simulations are described, following the collapse of the core, fragmentation and the…

Astrophysics · Physics 2009-11-10 Clare L. Dobbs , Ian A. Bonnell , Paul C. Clark

Inelastic collapse is found in a two-dimensional system of inelastic hard disks confined between two walls which act as an energy source. As the coefficient of restitution is lowered, there is a transition between a state containing small…

Soft Condensed Matter · Physics 2009-10-31 Jan Tobochnik

Star formation begins with the gravitational collapse of a dense core inside a molecular cloud. As the collapse progresses, the centre of the core begins to heat up as it becomes optically thick. The temperature and density in the centre…

Solar and Stellar Astrophysics · Physics 2015-06-16 N. Vaytet , G. Chabrier , E. Audit , B. Commercon , J. Masson , J. Ferguson , F. Delahaye

Three bright molecular line sources in G333 have recently been shown to exhibit signatures of infall. We describe a molecular line radiative transfer modelling process which is required to extract the infall signature from Mopra and Nanten2…

Astrophysics of Galaxies · Physics 2016-04-20 B. Wiles , N. Lo , M. P. Redman , M. R. Cunningham , P. A. Jones , M. G. Burton , L. Bronfman

We present an idealized, spherical model of the evolution of a magnetized molecular cloud due to ambipolar diffusion. This model allows us to follow the quasi-static evolution of the cloud's core prior to collapse and the subsequent…

Astrophysics · Physics 2009-10-30 P. N. Safier , C. F. McKee , S. W. Stahler

Using a generalized self-similar secondary infall model, which accounts for tidal torques acting on the halo, we analyze the velocity profiles of halos in order to gain intuition for N-body simulation results. We analytically calculate the…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-23 Phillip Zukin , Edmund Bertschinger

{It has recently been proposed that giant molecular complexes form at the sites where streams of diffuse warm atomic gas collide at transonic velocities.} {We study the global statistics of molecular clouds formed by large scale colliding…

Astrophysics · Physics 2009-11-13 P. Hennebelle , R. Banerjee , E. Vazquez-Semadeni , R. Klessen , E. Audit

We investigate the formation of spherical cosmological structures following both dark matter and gas components. We focus on the dynamical aspect of the collapse assuming an adiabatic, $\gamma = 5/3$, fully ionized primordial plasma. We use…

Astrophysics · Physics 2009-10-30 Jean-Pierre CHIEZE , Romain Teyssier , Jean-Michel Alimi

In this paper, we study the dynamics of a hollow spherical matter collapsing with very large initial velocity. The spacetime is initially very similar to the Vaidya solution, and the deviations from this background are treated…

General Relativity and Quantum Cosmology · Physics 2009-01-27 Zahid Ahmad , Tomohiro Harada , Ken-ichi Nakao , M. Sharif

In this work, the gas infall and the formation of outflows around low and high mass protostars are investigated. A radial self-similar approach to model the transit of the molecular gas around the central object is employed. We include…

Astrophysics · Physics 2009-11-13 C. Combet , T. Lery , G. C. Murphy

Super-sonic turbulence fragments molecular clouds (MC) into a very complex density field with density contrasts of several orders of magnitude. A fraction of the gas is locked into dense and gravitationally bound cores, which collapse as…

Astrophysics · Physics 2007-05-23 Paolo Padoan , AAke Nordlund , Ornolfur Einar Rognvaldsson , Alyssa Goodman

To date, most numerical simulations of molecular clouds, and star formation within them, assume a uniform density sphere or box with an imposed turbulent velocity field. In this work, we select molecular clouds from galactic scale…

Astrophysics of Galaxies · Physics 2015-06-23 Ramon Rey-Raposo , Clare Dobbs , Ana Duarte-Cabral

Hydrodynamical calculations in three space dimensions of the collapse of an isothermal, centrally condensed, rotating 1 M\sol protostellar cloud are presented. A numerical algorithm involving nested subgrids is used to resolve the region…

Astrophysics · Physics 2007-05-23 Andi Burkert , Peter Bodenheimer

The gravitational collapse of a spherical cloud core is investigated by numerical calculations. The initial conditions of the core lie close to the critical Bonnor-Ebert sphere with a central density of \sim 10^4 cm^{-3} in one model…

Astrophysics · Physics 2009-11-10 Yuri Aikawa , Eric Herbst , Helen Roberts , Paola Caselli

The evolution of collapsing clouds embedded in different star-forming environments is investigated using three-dimensional non-ideal magnetohydrodynamics simulations considering different cloud metallicities ($Z/\thinspace Z_\odot$ = 0,…

Solar and Stellar Astrophysics · Physics 2019-04-24 Koki Higuchi , Masahiro N. Machida , Hajime Susa

We performed $42$ simulations of the first star formation with initial supersonic gas flows relative to the dark matter at the cosmic recombination era. Increasing the initial streaming velocities led to delayed halo formation and increased…

Astrophysics of Galaxies · Physics 2023-09-06 Shingo Hirano , Youcheng Shen , Sho Nishijima , Yusuke Sakai , Hideyuki Umeda

The current study was developed to provide a database of relatively simple numerical simulations of protostellar collapse, as a template library for observations of cores and very young protostars, and for researchers who wish to test their…

Solar and Stellar Astrophysics · Physics 2018-08-08 Neil Vaytet , Troels Haugbølle

Using a two-dimensional hydrodynamics code (PROMETHEUS), we study the continued evolution of rotating massive helium stars whose iron core collapse does not produce a successful outgoing shock, but instead forms a black hole. We study the…

Astrophysics · Physics 2009-10-31 A. MacFadyen , S. E. Woosley