Abstract
ABSTRACT Galactic absorption line spectra can now yield valuable information bout the internal kinematics beyond the classical measures of mean velocity and (gaussian) velocity dispersion. An application of a new algorithm to the photometrically normal disk galaxy NGC 7217 has revealed that around 30% of the stars circulate in the opposite sense to the majority. The subtle, serendipitous nature of the discovery raises the possibility that this situation may not be uncommon. NGC 7217 and the previously-discovered case of NGC 4550 (in which both directions of circulation are equally populated) point towards substantial secondary infall of material with variable angular momentum, and suggest a possible explanation of the decrease of bulge to disk ratio with strengthening spiral structure along the Hubble sequence.
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