The Symmetry, Color, and Morphology of Galaxies

Abstract

The structural symmetry of forty-three face-on galaxy images in the R(65 0 nm) and J(450 nm) bands are measured to determine the usefulness of symmetry a s a morphological parameter. Each galaxy image is rotated by $180$°and subtr acted from the original to obtain a quantitative value for its structural symmet ry. The symmetry numbers computed for the sample are then compared with RC3 mor phological types, color \& absolute blue magnitudes. A strong correlation betw een color and symmetry is found, and the RC3 Hubble sequence is found to be one of increasing asymmetry. The use of symmetry as a morphological parameter, and the possible causes of the asymmetries are discussed.