We have attempted to determine the pattern speed of two barred spiral galaxies, NGC 1398 and NGC 3319. Observations of the 21-cm neutral hydrogen line were made at the VLA for both galaxies, using two configurations, the C and D. NGC 1398 has an inner ring and an outer pseudoring(s), both morphological features believed to be associated with resonances. Using a rotation curve derived from the 21-cm kinematic data, coupled with optical photometric images, we experiment with several possible options for the pattern speed, including a model with two pattern velocities. The neutral hydrogen surface density shows a large depleted region in the center of this galaxy, making a Canzian analysis difficult. Our recent observations of NGC 3319 show the neutral hydrogen surface density to be complex. The galaxy is gas rich in the center with a prominent neutral hydrogen bar. Further out in the disk several spiral features are observed. The rotation curve is rising and noncircular velocity perturbations appear small. We subtract the fitted rotation curve from the data and examine the residual pattern.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1994