Publication Abstracts

Russell and Roberts 1993

Russell, W.S., and W.W. Roberts, Jr, 1993: Analysis of the distribution of pitch angles in model galactic disks: Numerical methods and algorithms. Astrophys. J., 414, 86-97, doi:10.1086/173059.

Numerical methods and algorithms are developed for analyzing the morpology of global and local structure in prototype and observed disk-shaped galaxies. One prototype spiral galaxy, taken from the 1992 theoretical-computational studies of Roberts et al., serves as the representative candidate to be analyzed in this paper. From the computed distribution of the gaseous component, "partitioning" methods based on nearest-neighbor and Voronoi polyhedra calculations are applied to capture regions of high-population gas density associated with local arm segments, spurs, feathers, and secondary features. The pitch angle and length of each of these features are determined using least-squares procedures minimizing perpendicular distances from data points to the regression curve in adapted logarithmic spiral coordinates. The resulting least-squares approximations are further checked for goodness of fit using the Kolmogorov-Smirnov test. Despite the fact that the representative prototype model galaxy is driven by an underlying global two-armed density wave of 10-15° pitch angle, the gas response is found to exhibit many local and mesoscale spiral features of much greater pitch angle. These features are attributed to the self-gravitational effects of the gas itself on local scales. Prominent peaks are found in the computed pitch angle distribution between 20° and 40°; these are attributed to spurs and local arm segments that branch off the underlying 10-15° modal density-wave-driven global spiral pattern. Prominent highly inclined spurs and feathers in the outer half of the prototype galaxy are found to give rise to a peak pitch angle distribution between 50° and 55°.

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BibTeX Citation

@article{ru09000a,
  author={Russell, W. S. and Roberts, Jr, W. W.},
  title={Analysis of the distribution of pitch angles in model galactic disks: Numerical methods and algorithms},
  year={1993},
  journal={Astrophys. J.},
  volume={414},
  pages={86--97},
  doi={10.1086/173059},
}

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RIS Citation

TY  - JOUR
ID  - ru09000a
AU  - Russell, W. S.
AU  - Roberts, W. W., Jr
PY  - 1993
TI  - Analysis of the distribution of pitch angles in model galactic disks: Numerical methods and algorithms
JA  - Astrophys. J.
VL  - 414
SP  - 86
EP  - 97
DO  - 10.1086/173059
ER  -

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