The long bar as seen by the VVV survey: I. Colour-magnitude diagrams

TL;DR

This study uses VVV survey data to analyze the inner Milky Way, revealing the structure and orientation of the Long Bar and its impact on the Galactic disc through detailed colour-magnitude diagrams.

Contribution

It provides new insights into the Long Bar's orientation, its stellar population, and its influence on the inner Galactic structure using deep near-infrared observations.

Findings

Identification of the Long Bar with an angle of 41±5 degrees.

Detection of a stellar overdensity indicating recent star formation.

Evidence of disc truncation within 5 kpc due to the bar's potential.

Abstract

The VISTA Variable Survey (VVV) is able to map the Galaxy at l<0 with an unpaired depth (at least 3 mag deeper than 2MASS), opening new possibilities for studying the inner structure of the Milky Way. In this paper we concentrate on the exploitation of these data to better understand the spatial disposition and distribution of the structures present in the inner Milky Way, particularly the Long Bar and its interaction with the inner disc. The observations show the presence of a clear overdensity of stars with associated recent stellar formation that we interpret as the traces of the Long Bar, and we derive an angle for it of 41+/-5 with the Sun-Galactic centre line, touching the disc near l=27 and l=-12. The colour-magnitude diagrams presented here also show a lack of disc stars in several lines of sight, a fact that we associate with the truncation of the disc by the potential of this bar for Galactocentric radius less than 5kpc.