Other
Scientific paper
Dec 2007
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007aas...21114203m&link_type=abstract
American Astronomical Society, AAS Meeting #211, #142.03; Bulletin of the American Astronomical Society, Vol. 39, p.994
Other
Scientific paper
Using particle integrations of more than a million particles I explore the effect of spiral arms and the Galactic bar on the velocity distribution in the Milky Way disk. Three topics are explored: 1) heating due to multiple spiral patterns; 2) the effect of spiral and bar perturbations on Oort constant measurements; 3) signatures of spiral structure in large Galactic radial velocity surveys.
I find that stochastic heating is induced by interactions between two steady state spiral density waves moving at different pattern speeds. This new heating mechanism differs from others because it predicts that the velocity distribution is highly dependent upon position in the Galaxy.
I find that a two-armed spiral density wave affects measurements of the Oort constants introducing systematic errors in A and B of order 5 km/s/kpc. Oort's |C|, on average, is larger for lower stellar velocity dispersions, contrary to recent measurements (Olling & Dehnen 2003). This discrepancy is resolved by considering the effect of the Galactic bar on the local stellar velocity distribution. By comparing measurements of C with my simulations I improve on previous constraints on the bar, finding that the bar pattern speed Omegab/Omega0=1.87±0.04, where Omega0 is the local angular rotation frequency, and the bar angle lies within 20[deg]<=phi0<=45[deg].
By simulating pencil-beam and all-sky Galactic radial velocity surveys I show how the statistical kinematic properties of stars can be used to infer spiral structure parameters. Spiral pattern speeds can be estimated from the location of rings of increased velocity dispersion caused by Lindblad resonances. The angle of the pattern with respect to the Sun can also be measured.
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