New Red Supergiant Stars in the other side of our Galaxy

TL;DR

This study identifies 474 red supergiant stars on the far side of the Milky Way using a novel method combining OGLE and Gaia data, revealing their distribution and Galactic structure insights.

Contribution

Introduces a new method for identifying far-side RSGs and provides a comprehensive catalogue that enhances understanding of Galactic structure and stellar evolution.

Findings

474 new RSGs identified on the far side of the Galaxy

Distances estimated with 13% uncertainty, revealing distribution up to 30 kpc from the Galactic center

Distribution supports the Galactic disk flare model

Abstract

Red supergiant stars (RSGs) are massive stars in a late stage of evolution, crucial for understanding stellar life cycles and Galactic structure. However, RSGs on the far side of our Galaxy have been underexplored due to observational challenges. In this study, we introduce a novel method and present a new catalogue comprising 474 RSGs situated on the far side of the Milky Way, sourced from the OGLE-III catalogue of Variable Stars (OIII-CVS). The identification of these RSGs was made possible by analyzing the granulation parameters extracted from OGLE I-band time-series data and the stellar parameters from Gaia DR3. Additionally, we estimate the distances to these RSGs using an empirical relation between their characteristic amplitude, absolute magnitude, and intrinsic color, achieving a distance uncertainty of 13%. These newly identified RSGs are distributed at Galactocentric distances between 0 and 30kpc, and reside roughly 1 to 4kpc above and below the Galactic plane. This distribution provides new insights into the structure of the Milky Way, particularly at its outer boundaries. Our results reveal that the vertical distribution of these RSGs is consistent with the flare structure of the Galactic disk, confirming that the far side of the Milky Way exhibits a similar flaring pattern to the near side. This catalogue offers a valuable resource for future detailed studies of RSGs and contributes to a more comprehensive understanding of the Galactic structure and stellar evolution.