1997/10/06 by Mark R. Metzger, John A. R. Caldwell, Paul L. Schechter · 2 citations
Physics and Astronomy · Social Sciences · #Astronomy and Astrophysical Research #Cepheid variable #Cosmic distance ladder #Educational Leadership and Practices #Galaxy rotation curve #Kinematics #RR Lyrae variable #Radial velocity #Rotation (mathematics) #Rotational symmetry #Scale (ratio) #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/300198
36 pages, LaTeX, 10 figures
arxiv created 1997/10/06 · openalex publication_date 1998/02/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
A catalog of Cepheid variables is used to probe the kinematics of the Galactic disk. Radial velocities are measured for eight distant Cepheids toward l = 300°; these new Cepheids provide a particularly good constraint on the distance to the Galactic center, R 0 . We model the disk with both an axisymmetric rotation curve and one with a weak elliptical component, and find evidence for an ellipticity of 0.043 ± 0.016 near the Sun. Using these models, we derive R 0 = 7.66 ± 0.32 kpc and v circ = 237 ± 12 km s -1 . The distance to the Galactic center agrees well with recent determinations from the distribution of RR Lyrae variables and disfavors most models with large ellipticities at the solar orbit.