3-Dimensional Kinematics in low foreground extinction windows of the Galactic Bulge: Radial Velocities for 6 bulge fields

TL;DR

This paper introduces a new method combining HST data and spectroscopy to measure 3D stellar kinematics in the Galactic bulge, revealing a stellar bar through vertex deviation in six low-extinction fields.

Contribution

The study develops a novel technique for 3D kinematic measurements in crowded bulge fields, providing new insights into the bulge's structure and confirming the stellar bar presence.

Findings

Detection of vertex deviation indicating a stellar bar

Successful application of combined HST and spectroscopic data

Kinematic data for six bulge fields

Abstract

The detailed structure of the Galactic bulge still remain 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. 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. 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.