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There exists observational evidence that the interstellar medium has a fractal structure in a wide range of spatial scales. The measurement of the fractal dimension (Df) of interstellar clouds is a simple way to characterize this fractal…

Astrophysics · Physics 2011-02-11 Nestor Sanchez , Emilio J. Alfaro , Enrique Perez

The interstellar medium seems to have an underlying fractal structure which can be characterized through its fractal dimension. However, interstellar clouds are observed as projected two-dimensional images, and the projection of a…

Astrophysics · Physics 2007-05-23 Nestor Sanchez , Emilio J. Alfaro , Enrique Perez

The interstellar medium is structured as a hierachy of gas clouds, that looks self-similar over 6 orders of magnitude in scales and 9 in masses. This is one of the more extended fractal in the Universe. At even larger scales, the ensemble…

Astrophysics · Physics 2018-03-28 F. Combes

The geometric characteristics of dust clouds provide important information on the physical processes that structure such clouds. One of such characteristics is the $2D$ fractal dimension $D$ of a cloud projected onto the sky plane. In…

Estimates of the fractal dimension $D$ of the set of galaxies in the universe, based on ever improving data sets, tend to settle on $D\approx 2$. This result raised a raging debate due to its glaring contradiction with astrophysical models…

It is known that the gas has a fractal structure in a wide range of spatial scales with a fractal dimension that seems to be a constant around Df = 2.7. It is expected that stars forming from this fractal medium exhibit similar fractal…

Astrophysics · Physics 2009-06-23 Nestor Sanchez , Emilio J. Alfaro

Observations of interstellar gas clouds are typically limited to two-dimensional (2D) projections of the intrinsically three-dimensional (3D) structure of the clouds. In this study, we present a novel method for relating the 2D projected…

Astrophysics of Galaxies · Physics 2019-06-05 James R. Beattie , Christoph Federrath , Ralf S. Klessen

In the interstellar medium, as well as in the Universe, large density fluctuations are observed, that obey power-law density distributions and correlation functions. These structures are hierarchical, chaotic, turbulent, but are also…

Astrophysics · Physics 2016-08-30 Francoise Combes

We study the distribution of stars, HII regions, molecular gas, and individual giant molecular clouds in M33 over a wide range of spatial scales. The clustering strength of these components is systematically estimated through the fractal…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-08 Nestor Sanchez , Neyda Anez , Emilio J. Alfaro , Mary Crone Odekon

We study the physical properties derived from interstellar cloud complexes having a fractal structure. We first generate fractal clouds with a given fractal dimension and associate each clump with a maximum in the resulting density field.…

Astrophysics · Physics 2008-11-26 Nestor Sanchez , Emilio J. Alfaro , Enrique Perez

Several two-dimensional studies in spiral galaxies show that HII star formation regions have a fractal distribution, with a fractal dimension of approximately 2.3. In this work, the fractal dimension is calculated through the box-counting…

Astrophysics of Galaxies · Physics 2020-08-04 Canavesi Tobias , Hurtado Santiago

The fractal dimension $D$ is used to map the large-scale galaxy distribution in the Universe by color types: blue, green and red. Using a $NUVrK$-complete COSMOS2020 subsample of 618,952 galaxies observed up to $z=4$, number densities were…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-05 Ana Elisa Lima , Julianne C. Soares , Ana Carolina S. Tavares , Mariana V. Taveira , Sharon Teles , Amanda R. Lopes , Marcelo B. Ribeiro

Evidence is presented that the galaxy distribution can be described as a fractal system in the redshift range of the FDF galaxy survey. The fractal dimension $D$ was derived using the FDF galaxy volume number densities in the spatially…

Cosmology and Nongalactic Astrophysics · Physics 2014-10-22 G. Conde-Saavedra , A. Iribarrem , Marcelo B. Ribeiro

Most of the known methods for estimating the fractal dimension of fractal sets are based on the evaluation of a single geometric characteristic, e.g. the volume of its parallel sets. We propose a method involving the evaluation of several…

Metric Geometry · Mathematics 2015-06-22 Evgeny Spodarev , Peter Straka , Steffen Winter

Clouds in observations are fractals: they show self-similarity across scales ranging from one to 1000 km. This includes individual storms and large-scale cloud structures typical of organised convection. It is not known whether global…

Atmospheric and Oceanic Physics · Physics 2022-01-05 Hannah M. Christensen , Oliver G. A. Driver

The methods of determining the fractal dimension and irregularity scale in simulated galaxy catalogs and the application of these methods to the data of the 2dF and 6dF catalogs are analyzed. Correlation methods are shown to be correctly…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Nikita Yu. Lovyagin

The fractal dimension of large-scale galaxy clustering has been demonstrated to be roughly $D_F \sim 2$ from a wide range of redshift surveys. If correct, this statistic is of interest for two main reasons: fractal scaling is an implicit…

General Relativity and Quantum Cosmology · Physics 2010-10-27 J. R. Mureika

The fractal structure of star formation on large scales in disk galaxies is studied using the size distribution function of stellar aggregates in kpc-scale star fields. Achival HST images of 10 galaxies are Gaussian smoothed to define the…

Astrophysics · Physics 2009-10-31 Bruce G. Elmegreen , Debra Meloy Elmegreen

Supersonic turbulence is a key player in controlling the structure and star formation potential of molecular clouds (MCs). The three-dimensional (3D) turbulent Mach number, $\mathcal{M}$, allows us to predict the rate of star formation.…

Astrophysics of Galaxies · Physics 2019-07-17 James R. Beattie , Christoph Federrath , Ralf S. Klessen , Nicola Schneider

Gas cloud models taking into account the recently disclosed fractal structure of cold gas are set up, showing that large errors in the classical gas mass determination based on smooth cloud models can easily follow if the gas is in reality…

Astrophysics · Physics 2011-05-23 D. Pfenniger , F. Combes
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