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Paper: The Outer Banks of the Island Universes: A Spectroscopic Perspective
Volume: 396, Formation and Evolution of Galaxy Disks
Page: 193
Authors: Christlein, D.; Zaritsky, D.
Abstract: We have carried out a survey of the outer disks of nearby disk galaxies using optical spectroscopy. Multi-hour spectroscopy reveals Hα emission far beyond the typical extent of optical rotation curves, to approximately 50% beyond the optical radius R25, and yields information on kinematics, star formation, and metallicities in the outer disk. Here, we report on the kinematics. In a sample of 16 predominantly late-type, optically isolated and undisturbed galaxies, we find evidence for kinematic anomalies in two cases: emission regions that do not obey disk-like kinematics, and a kinematically broad, low-surface brightness component of the Hα line.
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