The Shape and Scale of Galactic Rotation from Cepheid Kinematics
Abstract
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 deg 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.
- Publication:
-
The Astronomical Journal
- Pub Date:
- February 1998
- DOI:
- 10.1086/300198
- arXiv:
- arXiv:astro-ph/9710055
- Bibcode:
- 1998AJ....115..635M
- Keywords:
-
- Cepheid Variables;
- Galactic Structure;
- Galactic Rotation;
- Radial Velocity;
- Calibrating;
- Astrophysics;
- STARS: VARIABLES: CEPHEIDS;
- GALAXY: FUNDAMENTAL PARAMETERS;
- GALAXY: KINEMATICS AND DYNAMICS;
- GALAXY: STRUCTURE;
- Astrophysics
- E-Print:
- 36 pages, LaTeX, 10 figures