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Observational and theoretical evidence suggests that a substantial population of molecular clouds (MCs) appear to be unbound, dominated by turbulent motions. However, these estimations are made typically via the so-called viral parameter…

We generalize the classic Bonnor-Ebert stability analysis of pressure-truncated, self-gravitating gas spheres, to include clouds with arbitrary equations of state. A virial-theorem analysis is also used to incorporate mean magnetic fields…

Astrophysics · Physics 2009-10-28 Dean E. McLaughlin , Ralph E. Pudritz

We study the instantaneous virial balance of clumps and cores (CCs) in 3D simulations of driven, MHD, isothermal molecular clouds (MCs). The models represent a range of magnetic field strengths in MCs from subcritical to non-magnetic…

The influence of rotation and magnetic fields on the physical properties of isothermal gas clouds is discussed. The presence of rotation and/or magnetic fields results in an increase of the critical cloud mass with respect to gravitational…

Astrophysics · Physics 2009-11-07 B. Vollmer , W. J. Duschl

Observations of magnetic field strengths imply that molecular cloud fragments are individually close to being in a magnetically critical state, even though both magnetic field and column density measurements range over two orders of…

Astrophysics · Physics 2007-05-23 Shantanu Basu

Turbulence governs the fragmentation of molecular clouds and plays a pivotal role in star formation. The persistence of observed cloud turbulence suggests it does not decay significantly within the turnover timescale, implying a recurrent…

Astrophysics of Galaxies · Physics 2025-09-15 Shibo Yuan , Hua-Bai Li

The virial ratio between kinetic and gravitational terms provides key insight into the balance of forces that confine a molecular cloud, but the clumpy and filamentary structures of resolved clouds make it difficult to evaluate this ratio…

Astrophysics of Galaxies · Physics 2019-06-17 Ayushi Singh , Christopher D. Matzner , Peter H. Jumper

Externally driven interstellar turbulence plays an important role in shaping the density structure in molecular clouds. Here we study the dynamical role of internally driven turbulence in a self-gravitating molecular cloud core. Depending…

Astrophysics of Galaxies · Physics 2020-03-04 Siyao Xu , Alex Lazarian

Molecular cloud observations show that clouds have non-thermal velocity dispersions that scale with the cloud size as $\sigma\propto R^{1/2}$ at constant surface density, and for varying surface density scale with both the cloud`s size and…

Astrophysics of Galaxies · Physics 2016-06-15 Juan C. Ibáñez-Mejía , Mordecai-Mark Mac Low , Ralf S. Klessen , Christian Baczynski

We study the effect that the dark matter background (DMB) has on the gravitational energy content and, in general, on the star formation efficiency of a molecular cloud (MC). We first analyze the effect that a dark matter halo, described by…

Solar and Stellar Astrophysics · Physics 2015-06-03 Andrés Suárez-Madrigal , Javier Ballesteros-Paredes , Pedro Colín , Paola D'Alessio

We present a numerical study of the balance between the gravitational (Eg), kinetic (Ek), and magnetic (Em) energies of structures within a hub-filament system in a simulation of the formation and global hierarchical collapse (GHC) of a…

Astrophysics of Galaxies · Physics 2023-06-07 Vianey Camacho , Enrique Vázquez-Semadeni , Manuel Zamora-Avilés , Aina Palau

We study effect of magnetic field on massive dense core formation in colliding unequal molecular clouds by performing magnetohydrodynamic simulations with sub-parsec resolution (0.015 pc) that can resolve the molecular cores. Initial clouds…

Astrophysics of Galaxies · Physics 2020-07-23 Nirmit Sakre , Asao Habe , Alex R. Pettitt , Takashi Okamoto

We study numerically the formation of molecular clouds in large-scale colliding flows including self-gravity. The models emphasize the competition between the effects of gravity on global and local scales in an isolated cloud. Global…

We simulate the formation of molecular clouds in colliding flows of warm neutral medium with the adaptive mesh refinement code {\sc Flash}. We include a chemical network to treat heating and cooling and to follow the formation of molecular…

Astrophysics of Galaxies · Physics 2022-08-26 Michael Weis , Stefanie Walch , Daniel Seifried , Shashwata Ganguly

We discuss the effects of the magnetic field observed in molecular clouds on the process of star formation, concentrating on the phase of gravitational collapse of low-mass dense cores, cradles of sunlike stars. We summarize recent analytic…

Astrophysics of Galaxies · Physics 2015-06-23 Susana Lizano , Daniele Galli

Gravity plays important roles in the evolution of molecular clouds. We present an acceleration mapping method to estimate the acceleration induced by gravitational interactions in molecular clouds based on observational data. We find that…

Astrophysics of Galaxies · Physics 2016-03-22 Guang-Xing Li , Andi Burkert , Tom Megeath , Friedrich Wyrowski

It has been paid little or no attention to the implications that turbulent fragmentation has on the validity of at least six common assumptions on the Virial Theorem (VT), which are: (i) the only role of turbulent motions within a cloud is…

Astrophysics · Physics 2009-11-11 Javier Ballesteros-Paredes

In this paper, we review some of the properties of dense molecular cloud cores. The results presented here rely on three-dimensional numerical simulations of isothermal, magnetized, turbulent, and self-gravitating molecular clouds (MCs) in…

Astrophysics · Physics 2008-08-29 Sami Dib , Roberto Galvan-Madrid , Jongsoo Kim , Enrique Vazquez-Semadeni

Using the 3D density distribution derived from the 3D dust map of the solar neighborhood, the gravitational potential is obtained by solving the Poisson equation, from which the tidal tensor is computed. In the optimal decomposition, the…

Astrophysics of Galaxies · Physics 2025-03-24 J. W. Zhou

Compression in giant molecular cloud (GMC) collisions is a promising mechanism to trigger formation of massive star clusters and OB associations. We simulate colliding and non-colliding magnetised GMCs and examine the properties of…

Astrophysics of Galaxies · Physics 2023-04-05 Chia-Jung Hsu , Jonathan C. Tan , Duncan Christie , Yu Cheng , Theo J. O'Neill
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