# Structure of our Galactic Bulge from CN Measurements

## TL;DR

This study investigates the structure of the Galactic bulge using CN measurements, providing evidence supporting an X-shaped bulge with a minor second-generation star component, challenging previous interpretations of red clump differences.

## Contribution

The paper offers a reanalysis of CN distribution data, using empirical simulations to support the X-shaped bulge model and refute the multiple population explanation for red clump differences.

## Key findings

- CN distributions are consistent with an X-shaped bulge structure.
- Minor second-generation star fraction in the bulge is about 2-3%.
- Data do not support multiple stellar populations causing red clump differences.

## Abstract

The double red clumps (DRCs) are now dominantly believed to be the strong observational line of evidence of the so-called X-shaped Galactic bar structures. Recently, Lee et al. reported a subtle mean \ds\ difference between the DRCs and suggested a dichotomic picture that can be seen in globular clusters: the faint red clump is the first generation, while the bright red clump corresponds to the second generation (SG). They argued that the magnitude difference between the DRCs is due to different stellar populations, and is not due to the geometric difference between the DRCs. Our reanalysis shows that their data do not appear to support the idea of the multiple population-induced DRCs in our Galactic bulge. We perform fully empirical Monte Carlo simulations and find that the shape of the \ds\ distributions is the most stringent evidence to pursue. Our results strongly suggest that the CN distributions toward the Galactic bulge are qualitatively consistent with the X-shaped Galactic bulge with a minor fraction of the SG of about 2 -- 3\%.