Galatic HII region IRAS 17149$-$3916 -- A multiwavelength study

TL;DR

This multiwavelength study of the Galactic HII region IRAS 17149-3916 combines radio, infrared, and submillimeter data to analyze its morphology, star formation activity, and core properties, revealing complex structures and potential high-mass star formation sites.

Contribution

It provides the first low-frequency radio continuum observations of this region and integrates multiwavelength data to understand its morphology and star formation processes.

Findings

Ionized gas shows cometary morphology likely powered by an early type star.

Triggered star formation is observed at the tip of a pillar structure.

High-resolution ALMA data reveal cores consistent with hierarchical fragmentation.

Abstract

This paper presents a multiwavelength investigation of the Galactic HII IRAS 17149$-$3916. Using the Giant Meterwave Radio Telescope, India, first low-frequency radio continuum observations at 610 and 1280 MHz for this region are presented. The ionized gas emission displays an interesting cometary morphology which is likely powered by the early type source, E4 (IRS-1). The origin of the cometary morphology is discussed under the framework of the widely accepted bow shock, champagne flow, and clumpy cloud mechanisms. The mid- and far-infrared data from Spitzer-GLIMPSE and Herschel-Hi-GAL reveal a complex network of pillars, clumps, bubble, filaments, and arcs suggesting the profound influence of massive stars on the surrounding medium. Triggered star formation at the tip of an observed pillar structure is reported. High-resolution ALMA continuum data show a string of cores detected within the identified clumps. The core masses are well explained by thermal Jeans fragmentation and support the hierarchical fragmentation scenario. Four `super-Jeans' cores are identified which, at the resolution of the present data set, are suitable candidates to form high-mass stars.