A study of the massive star forming region M8 using Spitzer IRAC images

TL;DR

This study uses Spitzer IRAC images to analyze star formation in the M8 region, identifying numerous young stellar objects, their clustering, and emission features related to star formation processes.

Contribution

It provides detailed IRAC-based identification of YSOs, their clustering, and diagnostic emission regions in M8, highlighting star formation triggered by HII regions and stellar winds.

Findings

Detected 64 Class 0/I and 168 Class II YSOs.

Identified clustering of YSOs with surface density 10-20 YSOs/pc².

Mapped emission regions indicating star formation activity.

Abstract

Spitzer IRAC images (3.6, 4.5, 5.8 and 8.0$\mu$m) and photometry of the star forming region M8 are presented. IRAC photometry reveals ongoing star formation in the M8 complex, with 64 Class 0/I and 168 Class II sources identified in several locations in the vicinity of sub-mm gas cores/clumps. Nearly 60% of these YSOs occur in about 7 small clusters. The spatial surface density of the clustered YSOs is determined to be about 10-20 YSOs/pc$^{2}$. Fresh star formation by the process of "collect and collapse" might have been triggered by the expanding HII regions and winds from massive stars. IRAC ratio images are generated and studied in order to identify possible diagnostic emission regions in M8. The image of 4.5$\mu$m/8.0$\mu$m reveals Br$\alpha$ counterpart of the optical Hourglass HII region, while the ratio 8.0$\mu$m/4.5$\mu$m indicates PAH emission in a cavity-like structure to the east of the Hourglass. The ratio maps of 3.6$\mu$m/4.5$\mu$m, 5.8$\mu$m/4.5$\mu$m and 8.0$\mu$m/4.5$\mu$m seem to identify PAH emission regions in the sharp ridges and filamentary structures seen East to West and NE to SW in M8 complex.