H II regions and supernova remnants associated with molecular clouds: A pilot study with the SARAO MeerKAT Galactic Plane Survey

TL;DR

This study investigates how massive stars and their remnants influence nearby molecular clouds, revealing that feedback from these stars affects cloud properties and potentially triggers star formation, based on combined radio and molecular line data.

Contribution

It provides the first detailed analysis of molecular clouds associated with H II regions and supernova remnants using combined MeerKAT and SEDIGISM data, highlighting their physical differences and evolutionary implications.

Findings

Associated clouds have higher mass and surface density.

Radio luminosity correlates with cloud mass and size.

Evidence supports feedback-triggered star formation.

Abstract

Massive stars (mass beyond 8 solMass) release vast amounts of energy into the interstellar medium through their stellar winds, photoionising radiation and supernova explosions. These processes may compress nearby regions, triggering further star formation, but the significance of triggered star formation across the Galactic disc is not well understood. This pilot study combines 1.3 GHz continuum data from the South African Radio Astronomy Observatory (SARAO) MeerKAT Galactic Plane Survey (SMGPS) with 13CO (2-1) data from the Structure, Excitation, and Dynamics of the Inner Galactic Interstellar Medium (SEDIGISM) survey to identify and examine molecular clouds associated with H II regions and supernovae remnants (SNRs). We focus on their physical properties and massive star formation potential. We identify 268 molecular clouds from the SEDIGISM tile covering the Galactic plane region between 341 and 343 longitude deg and latitude deg equal to or less 0.5, of which 90 clouds (34 per cent) are associated with SMGPS extended sources. Compared to unassociated clouds, we find that associated clouds exhibit significantly higher mean mass (9600 solMass vs. 2500 solMass ) and average gas surface density (104 solMass / pc^2 vs. 67 solMass / pc^2 ), and slightly elevated but comparable virial parameters. We also find that the size-linewidth scaling relation is steeper for associated clouds compared to unassociated clouds. In addition, radio luminosity shows a positive correlation with total complex mass, and the ratio L_radio/L_complex increases with source size, consistent with an evolutionary sequence where expanding H II regions progressively disrupt their natal molecular environment. These findings suggest an enhanced dynamical activity for the associated clouds and support the hypothesis that feedback from massive stars influences molecular cloud properties and may trigger star formation.