A Galactic Bar to Beyond the Solar Circle and its Relevance for Microlensing

TL;DR

This paper investigates the structure of the Galactic bar extending beyond the solar circle by analyzing Mira variable kinematics, revealing a bar-like feature that influences microlensing studies.

Contribution

It provides evidence for a Galactic bar extending beyond the solar circle based on Mira variable kinematics, linking bulge structure to microlensing implications.

Findings

Mira variables show orbit alignment indicating a Galactic bar.

The bar extends beyond the solar circle.

Implications for microlensing observations.

Abstract

The Galactic kinematics of Mira variables have been studied using infrared photometry, radial velocities, and Hipparcos parallaxes and proper motions. For Miras in the period range 145 to 200 days (probably corresponding to [Fe/H] in the range -0.8 to -1.3) the major axes of the stellar orbits are concentrated in the first quadrant of Galactic longitude. This is interpreted as a continuation of the bar-like structure of the Galactic Bulge out to the solar circle and beyond.