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Turbulence dissipation is an important process affecting the energy balance in molecular clouds, the birth place of stars. Previously, the rate of turbulence dissipation is often estimated with semi-analytic formulae from simulation.…

Instrumentation and Methods for Astrophysics · Physics 2018-10-10 Lei Qian , Di Li , Yang Gao , Haitao Xu , Zhichen Pan

Turbulence influences the structure and dynamics of molecular clouds, and plays a key role in regulating star formation. We therefore need methods to accurately infer turbulence properties of molecular clouds from position-position-velocity…

Astrophysics of Galaxies · Physics 2025-09-12 Jayashree Narayan , Aris Tritsis , Christoph Federrath

(Modified) The scaling of velocity fluctuation, dv, as a function of spatial scale L in molecular clouds can be measured from size-linewidth relations, principal component analysis, or line centroid variation. Differing values of the power…

Astrophysics · Physics 2009-11-10 C. M. Brunt , M. -M. Mac Low

Molecular clouds are supersonically turbulent. This turbulence governs the initial mass function and the star formation rate. In order to understand the details of star formation, it is therefore essential to understand the properties of…

Astrophysics of Galaxies · Physics 2015-06-17 Adam Ginsburg , Christoph Federrath , Jeremy Darling

We compare velocity structure in the Polaris Flare molecular cloud at scales ranging from 0.015 pc to 20 pc to simulations of supersonic hydrodynamic and MHD turbulence computed with the ZEUS MHD code. We use several different statistical…

Astrophysics · Physics 2007-05-23 Volker Ossenkopf , Mordecai-Mark Mac Low

The universality of interstellar turbulence is examined from observed structure functions of 27 giant molecular clouds and Monte Carlo modeling. We show that the structure functions, dv=v0 l^gamma, derived from wide field imaging of CO…

Astrophysics · Physics 2009-11-10 Mark Heyer , Christopher Brunt

The core velocity dispersion (CVD) is a potentially useful tool for studying the turbulent velocity field of molecular clouds. CVD is based on centroid velocities of dense gas clumps, thus is less prone to density fluctuation and reflects…

Astrophysics of Galaxies · Physics 2015-09-30 Lei Qian , Di Li , Stella Offner , Zhichen Pan

Velocity statistics is a direct probe of the dynamics of interstellar turbulence. Its observational measurements are very challenging due to the convolution between density and velocity and projection effects. We introduce the projected…

Astrophysics of Galaxies · Physics 2020-01-08 Siyao Xu

The structure and star formation activity of a molecular cloud are fundamentally linked to its internal turbulence. However, accurately measuring the turbulent velocity dispersion is challenging due to projection effects and observational…

Astrophysics of Galaxies · Physics 2021-12-22 Madeleine Stewart , Christoph Federrath

We examine how well the physical properties of clumps in turbulent molecular clouds can be determined by measurements of observed clump structures. We compare simulated observations of three-dimensional numerical models of isothermal,…

Astrophysics · Physics 2009-11-07 Javier Ballesteros-Paredes , Mordecai-M. Mac Low

We present a systematic analysis of the velocity structure functions (VSFs) of 167 molecular clouds with angular sizes greater than $\sim$176 arcmin$^2$ in three sectors of the Galactic mid-plane. We calculated the 1st- to 3rd-order VSFs…

The diffuse and translucent molecular clouds traced in absorption along the line of sight to strong background sources have so far been investigated mainly in the spectral domain because of limited angular resolution or small sizes of the…

Astrophysics of Galaxies · Physics 2019-03-13 V. Thiel , A. Belloche , K. M. Menten , A. Giannetti , H. Wiesemeyer , B. Winkel , P. Gratier , H. S. P. Müller , D. Colombo , R. T. Garrod

We look at various correlation functions, which include those that involve both the velocity and the vorticity fields, in two-dimensional (2D) isotropic homogeneous unforced turbulence. We adopt the more intuitive approach due to Kolmogorov…

Fluid Dynamics · Physics 2009-08-10 Sagar Chakraborty

The observational record of turbulence within the molecular gas phase of the interstellar medium is summarized. We briefly review the analysis methods used to recover the velocity structure function from spectroscopic imaging and the…

Astrophysics · Physics 2009-11-11 M. H. Heyer , C. Brunt

The measure of the third-order structure function, Y, is employed in the solar wind to compute the cascade rate of turbulence. In the absence of a mean field B0=0, Y is expected to be isotropic (radial) and independent of the direction of…

Solar and Stellar Astrophysics · Physics 2015-05-27 Andrea Verdini , Roland Grappin , Petr Hellinger , Simone Landi , Wolf-Christian Müller

[abridged] We determine the relationship between turbulence energy and gas density variance for 15 molecular clouds in the Solar neighbourhood. We use the linewidths of the CO molecule as the probe of the turbulence energy (sonic Mach…

Astrophysics of Galaxies · Physics 2017-12-06 Jouni Kainulainen , Christoph Federrath

We discuss the nature of the velocity dispersion vs. size relation for molecular clouds. In particular, we add to previous observational results showing that the velocity dispersions in molecular clouds and cores are not purely functions of…

Turbulence in curved spacetimes in general, and in the vicinity of black holes (BHs) in particular, represents a poorly understood phenomenon that is often analysed employing techniques developed for flat spacetimes. We here propose a novel…

General Relativity and Quantum Cosmology · Physics 2025-11-19 Rita Megale , Alejandro Cruz-Osorio , Giuseppe Ficarra , Mario Imbrogno , Claudio Meringolo , Leonardo Primavera , Luciano Rezzolla , Sergio Servidio

Aim: To study turbulence in the Orion Molecular Cloud (OMC1) by comparing observed and simulated characteristics of the gas motions. Method: Using a dataset of vibrationally excited H2 emission in OMC1 containing radial velocity and…

Astrophysics · Physics 2016-08-30 M. Gustafsson , A. Brandenburg , J. L. Lemaire , D. Field

Turbulence plays a major role in the formation and evolution of molecular clouds. The problem is that turbulent velocities are convolved with the density of an observed region. To correct for this convolution, we investigate the relation…

Astrophysics of Galaxies · Physics 2015-05-28 Julia Roman-Duval , Christoph Federrath , Christopher Brunt , Mark Heyer , James Jackson , Ralf Klessen
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