3-dimensional kinematics in low foreground extinction windows of the Galactic bulge. Radial velocities for six bulge fields: procedures and results

Abstract

Aims: The detailed structure of the Galactic bulge still remains uncertain. The strong difficulties of obtaining observations of stars in the Galactic bulge have hindered the acquisition of a kinematic representation for the inner kpc of the Milky Way. The observation of the 3-d kinematics in several low foreground extinction windows can solve this problem.
Methods: We have developed a new technique, which combines precise stellar HST positions and proper motions with integral field spectroscopy, in order to obtain reliable 3-d stellar kinematics in crowded fields of the Galactic center.
Results: In addition, we present results using the new techniques for six fields in our project. A significant vertex deviation has been found in some of the fields in agreement with previous determinations. This result confirms the presence of a stellar bar in the Galactic bulge.

Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile. European Southern Observatory (ESO) programme numbers 71.B-3048(A), 077.B-0600(A) and 079.B-0232(A).Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-2655. These observations are associated with proposals GO-8250, GO-9436, GO-9816 and GO-11655.