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It has been suggested that the peanut-shaped bulges seen in some edge-on disk galaxies are produced by central bars in these systems. Unfortunately, this association has proved difficult to establish observationally: peanut distortions in bulge isophotes are only measurable if a galaxy is viewed close to edge-on, whereas galactic bars can only be detected photometrically in more face-on systems. However, orbital motions in edge-on barred potentials produce a strong kinematic signature in the form of double-peaked line-of-sight velocity distributions with a characteristic ``figure-of-eight'' variation with radius. We have made spectroscopic observations of two edge-on galaxies with peanut-shaped bulges (NGC~5746 and NGC~5965), and they reveal exactly such line-of-sight velocity distributions in both their gaseous (emission line) and their stellar (absorption line) components. These data provide strong observational evidence that peanut-shaped bulges are a by-product of bar formation.
This research has been supported by a PPARC Advanced Fellowship (MM) and a Hubble Fellowship (KK).
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