The Split Red Clump of the Galactic Bulge from OGLE-III

TL;DR

This study detects a split in the red clump stars along multiple sightlines toward the Galactic Bulge, revealing two components with distinct brightness but similar color, indicating complex structure.

Contribution

It provides the first high-significance detection of a split red clump in the Galactic Bulge across multiple sightlines, revealing detailed structural features.

Findings

Two red clump components with ~0.5 mag brightness difference

Main component follows the Bulge distance-longitude relation

Secondary component's prominence increases away from the plane

Abstract

The red clump is found to be split into two components along several sightlines toward the Galactic Bulge. This split is detected with high significance toward the areas (-3.5<l<1,b<-5) and (l,b)=(0,+5.2), i.e., along the Bulge minor axis and at least 5 degrees off the plane. The fainter (hereafter ``main'') component is the one that more closely follows the distance-longitude relation of the Bulge red clump. The main component is ~0.5 magnitudes fainter than the secondary component and with an overall approximately equal population. For sightlines further from the plane, the difference in brightness increases, and more stars are found in the secondary component than in the main component. The two components have very nearly equal (V-I) color.