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A. M. Einbond, J. E. Rhoads (Kitt Peak National Observatory)
Recent photometric studies of nearby spiral galaxies suggest that spiral arms are major features in mass distribution. To look for this feature in our own Galaxy, we studied the kinematics of K giants toward the Galactic anticenter. From photometric observations we selected about 160 stars for further observation using the WIYN Hydra multi-fiber spectrograph. Spectra were used to calculate radial velocities, and distances were calculated by spectroscopic parallax.
We observe a range of radial velocity dispersions from 38.3 ±4.9 km/s at a heliocentric distance of 4 kpc to 21.6 ±2.7 km/s at a heliocentric distance of 7 kpc. From this we can estimate the arm to interarm mass density ratio to be between 2 and 5 and through dynamical modeling techniques obtain a more precise value. These values are consistent with photometric results for other spiral galaxies.
This research is supported by the Kitt Peak National Observatory site program of the Research Experiences for Undergraduates program, funded by the National Science Foundation.
The author(s) of this abstract have provided an email address for comments about the abstract: einbond@fas.harvard.edu