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A fundamental issue in star formation is understanding the precise mechanisms leading to the formation of prestellar cores, and their subsequent gravitationally unstable evolution. To address this question, we carefully construct a suite of…

Astrophysics of Galaxies · Physics 2025-05-13 Sanghyuk Moon , Eve C. Ostriker

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…

Astrophysics · Physics 2007-05-23 Philippe Andre , Arnaud Belloche , Patrick Hennebelle , Derek Ward-Thompson

Isolated low-mass stars are formed in dense cores of molecular clouds. In the standard picture, the cores are envisioned to condense out of strongly magnetized clouds through ambipolar diffusion. Most previous calculations based on this…

Astrophysics · Physics 2009-11-07 Zhi-Yun Li , Fumitaka Nakamura

(Abridged) Most massive protostars exhibit bipolar outflows. Nonetheless, there is no consensus regarding the mechanism at the origin of these outflows, nor on the cause of the less-frequently observed monopolar outflows. We aim to identify…

Solar and Stellar Astrophysics · Physics 2021-12-08 R. Mignon-Risse , M. González , B. Commerçon

In partially ionised plasmas, the magnetic field can become decoupled from the neutral gas and diffuse through it in a process known as ambipolar diffusion. Although ambipolar diffusion has been implemented in several grid codes, we here…

Solar and Stellar Astrophysics · Physics 2015-06-22 James Wurster , Daniel J. Price , Ben A. Ayliffe

Most numerical investigations on the role of magnetic fields in turbulent molecular clouds (MCs) are based on ideal magneto-hydrodynamics (MHD). However, MCs are weakly ionized, so that the time scale required for the magnetic field to…

Astrophysics · Physics 2009-11-13 Pak Shing Li , Christopher F. McKee , Richard I. Klein , Robert T. Fisher

Theoretically, stars have been formed from the collapse of cores in the molecular clouds. Historically, the core had been assumed as an singular isothermal sphere (SIS), and the collapse had been investigated by a self-similar manner. This…

Astrophysics of Galaxies · Physics 2015-05-19 Mohsen Nejad-Asghar

Simulations generally show that non-self-gravitating clouds have a lognormal column density ($\Sigma$) probability distribution function (PDF), while self-gravitating clouds with active star formation develop a distinct power-law tail at…

Astrophysics of Galaxies · Physics 2017-12-20 Sayantan Auddy , Shantanu Basu , Takahiro Kudoh

(Abridged) Context. Massive stars form in magnetized and turbulent environments, and are often located in stellar clusters. Their accretion mechanism, as well as the origin of their system's stellar multiplicity are poorly understood. Aims.…

Solar and Stellar Astrophysics · Physics 2021-08-11 R. Mignon-Risse , M. González , B. Commerçon , Joakim Rosdahl

The transport of angular momentum is capital during the formation of low-mass stars; too little removal and rotation ensures stellar densities are never reached, too much and the absence of rotation means no protoplanetary disks can form.…

Solar and Stellar Astrophysics · Physics 2018-07-04 Neil Vaytet , Benoît Commerçon , Jacques Masson , Matthias González , Gilles Chabrier

We investigate the formation of circumstellar disks and outflows subsequent to the collapse of molecular cloud cores with the magnetic field and turbulence. Numerical simulations are performed by using an adaptive mesh refinement to follow…

Solar and Stellar Astrophysics · Physics 2017-04-26 Tomoaki Matsumoto , Masahiro N. Machida , Shu-ichiro Inutsuka

We show that the ambipolar-diffusion--initiated fragmentation of molecular clouds leads simply and naturally to an initial core mass function (CMF) which is very similar to the initial stellar mass function (IMF) and in excellent agreement…

Solar and Stellar Astrophysics · Physics 2015-05-13 Matthew W. Kunz , Telemachos Ch. Mouschovias

The formation of stars is governed by the intricate interplay of nonideal magnetohydrodynamic (MHD) effects, gravity, and turbulence. Computational challenges have hindered a comprehensive 3D exploration of this interplay, posing a…

Astrophysics of Galaxies · Physics 2025-07-15 Aris Tritsis

We use a semianalytic approach that is calibrated to N-body simulations to study the evolution of self-interacting dark matter cores in galaxies. We demarcate the regime where the temporal evolution of the core density follows a…

Astrophysics of Galaxies · Physics 2020-03-18 Hiroya Nishikawa , Kimberly K. Boddy , Manoj Kaplinghat

We summarize the current status of the turbulent model of star formation in turbulent molecular clouds. In this model, clouds, clumps and cores form a hierarchy of nested density fluctuations caused by the turbulence, and either collapse or…

Astrophysics · Physics 2007-05-23 Enrique Vazquez-Semadeni

We numerically model evolution of magnetic fields inside a neutron star under the influence of ambipolar diffusion in the weak-coupling mode in the one-fluid MHD approximation. Our simulations are three-dimensional and performed in…

High Energy Astrophysical Phenomena · Physics 2022-11-09 Andrei P. Igoshev , Rainer Hollerbach

We investigate differences in the molecular abundances between magnetically super- and sub-critical prestellar cores, performing three-dimensional non-ideal magnetohydrodynamical (MHD) simulations with varying densities and magnetic field…

Astrophysics of Galaxies · Physics 2019-07-17 Felix D. Priestley , James Wurster , Serena Viti

Though flux freezing is a good approximation frequently assumed for molecular clouds, ambipolar diffusion (AD) is inevitable at certain scales. The scale at which AD sets in can be a crucial parameter for turbulence and the star formation…

Solar and Stellar Astrophysics · Physics 2015-05-18 Hua-bai Li , Martin Houde , Shih-ping Lai , T. K. Sridharan

Self-gravitating galactic halos composed of self-interacting dark matter exhibit the formation of a highly dense core at the galactic center--a gravothermal collapse. Analytic models to describe this evolution have been developed and…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-29 Marc Kamionkowski , Kris Sigurdson

For a molecular cloud clump to form stars some transport of magnetic flux is required from the denser, inner regions to the outer regions of the cloud, otherwise this can prevent the collapse. Fast magnetic reconnection which takes place in…

High Energy Astrophysical Phenomena · Physics 2015-06-11 M. R. M. Leão , E. M. de Gouveia Dal Pino , R. Santos-Lima , A. Lazarian