A search for scale-dependent morphology in five molecular cloud complexes
R. L. Dickman, M. Margulis, M. A. Horvath;
ApJ, 1990, 365, 586
ABSTRACT:IRAS 100 micron intensity images and 60 micron optical depth maps of five molecular
cloud complexes are analyzed using area-perimeter analysis.
It is found
that a noninteger Hausdorff dimension describes the shape of clouds and
condensations within the complexes; that is, cloud areas are generally a noninteger
power of perimeter, so that the projected two-dimensional shapes of these
objects are fractal.
The effect of noise on the cloud images is analyzed, and it
is demonstrated that this result is not an artifact but reflects a
fundamental irregularity of the clouds which probably arises from
turbulence.
The Hausdorff dimensions do not differ substantially from those found for
terrestrial and interstellar cirrus clouds.
No evidence of smooth morphology is
found, implying that the correlation length of the turbulence driving the
morphological irregularities within the clouds is less than 0.3 pc.
Strong evidence
of a measurable decline in Hausdorff dimension with decreasing scale is
also found.
KEYWORDS: infrared imagery, interstellar matter, molecular clouds, turbulence, hydrodynamic equations, infrared astronomy, infrared astronomy satellite, morphology
PERSOKEY:turbulence, ,
CODE: dickman90