ABSTRACT

Spiral galaxies are characterized by a flat disk containing a spiral structure emanating from a large central bulge. To an earthbound observer, some spiral galaxies appear to have an elliptical shape. This paper demonstrates that all spiral galaxies are essentially round disks, and that the apparent eccentricity of the ellipse is due to the orientation of the galaxy with respect to the observer. The study comprises two components. The first component is a computer simulation that utilizes one hundred simulated galaxies using randomly oriented cylinders. The second component considers a random sample of real galaxies using images from internet sources. The apparent rotation of a circular disk about the major axis of the apparent ellipse in the image plane is computed for each simulated and real galaxy in the sample. The distribution of apparent rotation is compared for both the simulated galaxy scenario and the random sample of real galaxy images. Despite a drop in the expected distribution for near edge-on galaxies, the analysis supports the hypothesis that spiral galaxies are round disks, with the apparent ellipse being the result of the orientation of the disk relative to the observer.

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Last Updated on 04/12/1999
By Brian von Konsky