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Paper: Does the Galaxy NGC4622 Have a Pair of Leading Arms?
Volume: 316, Order and Chaos in Stellar and Planetary Systems
Page: 270
Authors: Byrd, G.; Freeman, T.; Buta, R.
Abstract: Combined with ground-based Doppler shift observations, our Hubble Space Telescope observations of gas cloud silhouettes and bulge color asymmetries in the two-way arm galaxy, NGC4622, have indicated that it has a pair of arms which wind outward in the same clockwise (CW) sense on the sky as the disk orbital motion. This is against current conceptions of arm sense in spiral galaxies. We would like to verify these conclusions. The orbital motion of disk material can be ascertained by using the time delay between favorable points for gas cloud aggregation (where a peak of I emission occurs), the resulting star formation, and then the subsequent ionization and dispersal of the gas as the star complex lights up in the B band. We have observationally verified this I B time delay via the resonance ring in NGC3081. We use our HST color observations to verify the CW orbit angular sense in NGC4622, the same as the direction its pair of leading spiral arms wind outward.
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