2005/01/31 by Nestor Sanchez, Emilio J. Alfaro, Enrique Perez · 9 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Scientific Research and Discoveries #Statistical Mechanics and Entropy #astro-ph
paper · pdf · doi:10.1086/429553
published as Astrophys.J. 625 (2005) 849-856 · 27 pages, 13 figures, 1 table. Accepted for publication in ApJ. Minor changes
arxiv created 2005/02/18 · openalex publication_date 2005/05/27 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
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 three-dimensional fractal distorts its measured properties. Here we use simulated fractal clouds to study the relationship between the three-dimensional fractal dimension ( D f ) of modeled clouds and the dimension resulting from their projected images. We analyze different fractal dimension estimators: the correlation and mass dimensions of the clouds and the perimeter-based dimension of their boundaries ( D per ). We find the functional forms relating D f with the projected fractal dimensions, as well as their dependence on the image resolution, which allow us to estimate the "real" D f value of a cloud from its projection. The application of these results to Orion A indicates in a self-consistent way that 2.5 ≲ D f ≲ 2.7 for this molecular cloud, a value higher than the result D per + 1 ≃ 2.3 sometimes assumed in the literature for interstellar clouds.