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Volume and column density PDFs in molecular clouds are important diagnostics for understanding their general structure. We developed a novel approach to trace the cloud structure by varying the lower PDF cut-off and exploring a suggested…

Solar and Stellar Astrophysics · Physics 2013-08-02 Orlin Stanchev , Sava Donkov , Todor V. Veltchev , Rahul Shetty

Larson (1981) first noted a scaling relation between masses and sizes in molecular clouds that implies that these objects have approximately constant column densities. This original claim, based upon millimeter observations of carbon…

Astrophysics of Galaxies · Physics 2015-05-19 Marco Lombardi , Joao Alves , Charles J. Lada

We study the mass-density relationship n ~ m^x in molecular cloud condensations (clumps), considering various equipartition relations between their gravitational, kinetic, internal and magnetic energies. Clumps are described statistically,…

Solar and Stellar Astrophysics · Physics 2015-05-20 Sava Donkov , Todor Veltchev , Ralf S. Klessen

Despite over 30 years of study, the mass-area relationship within and among clouds is still poorly understood both observationally and theoretically. Modern extinction datasets should have sufficient resolution and dynamic range to…

We show that an array of singular density concentrations accounts for the scaling exponents observed in the luminous matter distribution in the Universe for scales below 10Mpc. This model provides a good description of the matter…

Astrophysics · Physics 2015-06-24 G. Murante , A. Provenzale , E. A. Spiegel , R. Thieberger

We present a model for describing the general structure of molecular clouds (MCs) at early evolutionary stages in terms of their mass-size relationship. Sizes are defined through threshold levels at which equipartitions between…

Astrophysics of Galaxies · Physics 2016-04-26 Todor V. Veltchev , Sava Donkov , Ralf S. Klessen

Simulations of molecular clouds often begin from highly idealised initial conditions, such as a uniform-density sphere with an artificially imposed turbulent velocity field. While the resulting structures may appear qualitatively similar to…

Astrophysics of Galaxies · Physics 2023-01-25 F. D. Priestley , P. C. Clark , A. P Whitworth

We revisit the mass-size relation of molecular cloud structures based on the column density map of the Cygnus-X molecular cloud complex. We extract 135 column density peaks in Cygnus-X and analyze the column density distributions around…

Astrophysics of Galaxies · Physics 2022-05-18 Yuchen Xing , Keping Qiu

We dendrogram the Leike et al. 2020 3D dust map, leveraging its $\sim 1$ pc spatial resolution to produce a uniform catalog of molecular clouds in the solar neighborhood. Using accurate distances, we measure the properties of 65 clouds in…

Astrophysics of Galaxies · Physics 2024-02-02 Shlomo Cahlon , Catherine Zucker , Alyssa Goodman , Charles Lada , João Alves

First-order statistics of scattered light is described using the representation of probability density cloud which visualizes a two-dimensional distribution for complex amplitude. The geometric parameters of the cloud are studied in detail…

Instrumentation and Methods for Astrophysics · Physics 2017-08-02 Natalia Yaitskova

A large number of astronomical phenomena exhibit remarkably similar scaling relations. The most well-known of these is the mass distribution $\mathrm{d} N/\mathrm{d} M\propto M^{-2}$ which (to first order) describes stars, protostellar…

Astrophysics of Galaxies · Physics 2018-04-25 David Guszejnov , Philip F. Hopkins , Michael Y. Grudić

The probability distribution function (PDF) of the mass surface density is an essential characteristic of the structure of molecular clouds or the interstellar medium in general. Observations of the PDF of molecular clouds indicate a…

Astrophysics of Galaxies · Physics 2015-06-18 Joerg Fischera

We have obtained column density maps for an unbiased sample of 120 molecular clouds in the third quadrant of the Milky Way mid-plane (b$\le |5|^{\circ}$) within the galactic longitude range from 195$^{\circ}$ to 225$^{\circ}$, using the…

Astrophysics of Galaxies · Physics 2022-08-31 Yuehui Ma , Hongchi Wang , Miaomiao Zhang , Chen Wang , Shaobo Zhang , Yao Liu , Chong Li , Yuqing Zheng , Lixia Yuan , Ji Yang

We investigate physical properties of molecular clouds in disc galaxies with different morphology: a galaxy without prominent structure, a spiral barred galaxy and a galaxy with flocculent structure. Our $N$-body/hydrodynamical simulations…

Astrophysics of Galaxies · Physics 2016-03-02 S. A. Khoperskov , E. O. Vasiliev , D. A. Ladeyschikov , A. M. Sobolev , A. V. Khoperskov

In this Letter we investigate the shape of the probability distribution of column densities (PDF) in molecular clouds. Through the use of low-noise, extinction-calibrated \textit{Herschel}/\textit{Planck} emission data for eight molecular…

Solar and Stellar Astrophysics · Physics 2015-06-23 Marco Lombardi , João Alves , Charles J. Lada

Structures in molecular ISM are observed to follow a power-law relation between the velocity dispersion and spatial size, known as Larson's first relation, which is often attributed to the turbulent nature of molecular ISM and imprints the…

Astrophysics of Galaxies · Physics 2024-10-22 Haoran Feng , Zhiwei Chen , Zhibo Jiang , Yuehui Ma , Yang Yang , Shuling Yu , Dongqing Ge , Wei Zhou , Fujun Du , Chen Wang , Shiyu Zhang , Yang Su , Ji Yang

Theoretical concepts in condensed matter physics are typically verified and also developed by exploiting computer simulations mostly in simple models. Predictions based on these usually isotropic models are often at odds with measurement…

Soft Condensed Matter · Physics 2020-11-13 K. Koperwas , A. Grzybowski , M. Paluch

A stochastic model relating the parameters of astrophysical structures to the parameters of their granular components is applied to the formation of hierarchical, large-scale structures from galaxies assumed as point-like objects. If the…

Cosmology and Nongalactic Astrophysics · Physics 2009-08-20 S. Capozziello , S. Funkhouser

{It is necessary to understand the dynamics of the atomic gas to use complex modeling and to carry out detailed comparisons between theoretical models and observations.}{In a companion paper, we present high resolution bidimensional…

Astrophysics · Physics 2007-05-23 P. Hennebelle , E. Audit , M. -A Miville-Deschenes

We consider the general problem of fitting a parametric density model to discrete observations, taken to follow a non-homogeneous Poisson point process. This class of models is very common, and can be used to describe many astrophysical…

Instrumentation and Methods for Astrophysics · Physics 2015-06-17 Marco Lombardi , Charles J. Lada , João Alves
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