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Session 10 - Spiral Galaxies.
Display session, Monday, June 10
Great Hall,
The structural symmetry of galaxies is an often quoted but rarely studied feature in extragalactic astronomy. This study finds the symmetries of fifty galaxies of varying morphologies from ellipticals to irregulars. The method used consists of rotating the image of a galaxy by 180 degrees and subtracting the rotated image by the original image. The sum of the pixels in the subtracted image is then divided by the sum of the pixels of the original image. This number, the symmetry number (S) is then a measure of the structural symmetry of the galaxy. It varies from 0 to 1, with S=0 belonging to a completely symmetric galaxy and S=1 belonging to a completely asymmetric galaxy.
This symmetry number (S) is then compared with other physical properties of the galaxies. Comparisons are made with (B-V) color, FIR emission, UV and H-alpha fluxes. A correlation is found between the symmetry number (S) and these physical quantities, indicating that that the symmetry number (S) can used as a indicator of the rate of star formation in galaxies.
