2007/03/31 by Ivan Minchev, I. Minchev, Jason Nordhaus +3 · 101 citations
Physics and Astronomy · #Adaptive optics and wavefront sensing #Astrophysics #Bar (unit) #Dispersion (optics) #Galactic Center #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gravitational potential #Optics #Physics #Stars #Stellar, planetary, and galactic studies #Velocity dispersion #astro-ph
paper · pdf · doi:10.1086/520578
published in The Astrophysical Journal 664(1), L31-L34 (IOP Publishing) · 4 pages, 2 figures, Accepted to ApJ Letters. Replaced with accepted version
openalex publication_date 2007/07/02 · arxiv created 2007/12/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Previous work has related the Galactic bar to structure in the local stellar velocity distribution. Here we show that the bar also influences the spatial gradients of the velocity vector via the Oort constants. By numerical integration of test particles we simulate measurements of the Oort C -value in a gravitational potential including the Galactic bar. We account for the observed trend that C is increasingly negative for stars with higher velocity dispersion. By comparing measurements of C with our simulations we improve on previous models of the bar, estimating that the bar pattern speed is Ω b /Ω 0 = 1.87 ± 0.04, where Ω 0 is the local circular frequency, and the bar angle lies within 20° ⩽ ϕ 0 ⩽ 45°. We find that the Galactic bar affects measurements of the Oort constants A and B less than ~2 km s -1 kpc -1 for the hot stars.