Stellar evolution in the outer Galaxy

TL;DR

This study develops a method to classify young stellar objects in the Outer Galaxy using combined near- and mid-infrared data, aiming to understand star formation in a different galactic environment.

Contribution

It introduces a new classification approach for YSOs and evolved stars in the Outer Galaxy using color-color diagrams from combined infrared surveys.

Findings

Successful separation of YSOs from evolved stars in the IRAC and MIPS data.

Initial identification of low- and intermediate-mass YSOs in the Outer Galaxy.

Foundation for future detailed analysis of stellar populations.

Abstract

We investigate the distribution of different classes of spectroscopically identified sources and theoretical models in the color-color diagrams (CCDs) combining the near-infrared (NIR) and mid-infrared (MIR) data to develop a method to classify Outer Galaxy sources detected with the Spitzer Space Telescope (hereafter Spitzer) SMOG survey in the IRAC 3.6 and 8.0 micrometer and MIPS 24 micrometer bands. We supplement the Spitzer data with the data from other satellite and ground-based surveys. The main goal of our study is to discover and characterize the population of intermediate- and low-mass young stellar objects (YSOs) in the Outer Galaxy and use it to study star formation in a significantly different environment than the Galaxy inside the solar circle. Since the YSOs can be confused with evolved stars in the MIR, these classes of objects need to be carefully separated. Here we present the initial results of our analysis using the Ks-[8.0] vs. Ks-[24] CCD as an example. The evolved stars separated from YSOs in the YSO selection process will be investigated in detail in the follow-up study.