The ellipticity of M31 globular clusters
Date
1989
Authors
Markle, Laura Marie
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Abstract
The ellipticity and orientation of seventeen globular clusters associated with the Andromeda Nebula (M31) have been measured using an isophotal method and a moment method. The measured ellipticities range from 0.024 to 0.212 with a mean value of 0.097 ± 0.017 No ellipticity variation is observed for these clusters. The M31 globular clusters are flatter than those associated with the Milky Way but their ellipticity distribution resembles that of the Large Magellanic Cloud globulars. The mechanism flattening the M31 globular clusters appears to be axial rotation of a size exceeding that of the Galactic globulars and/or anisotropic velocities of the cluster stars.