Testing Triggered Star Formation in Six H II Regions

TL;DR

This study examines six H II regions with specific morphologies to find evidence of triggered star formation, using infrared data, molecular gas analysis, and models to compare observed and predicted star formation scenarios.

Contribution

It provides a quantitative analysis of triggered star formation in H II regions by combining observational data with theoretical models and simulations.

Findings

Enhanced populations of YSOs on bright rims suggest triggered star formation.

Regions with blister morphology are more likely to show evidence of triggering.

Comparison with models supports collect and collapse and radiatively driven implosion scenarios.

Abstract

We investigated six H II regions with infrared, bright rimmed bubble or cometary morphology, in search of quantitative evidence for triggered star formation, both collect and collapse and radiatively driven implosion. We identified and classified 458 Young Stellar Objects (YSOs) in and around the H II regions. YSOs were determined by fitting a collection of radiative transfer model spectral energy distributions (SEDs) to infrared photometry for a large sample of point sources. We determined areas where there exist enhanced populations of relatively unevolved YSOs on the bright rims of these regions, suggesting that star formation has been triggered there. We further investigated the physical properties of the regions by using radio continuum emission as a proxy for ionizing flux powering the H II regions, and 13CO (1-0) observations to measure masses and gravitational stability of molecular clumps. We used an analytical model of collect and collapse triggered star formation, as well as a simulation of radiatively driven implosion, and thus we compare the observed properties of the molecular gas with those predicted in the triggering scenarios. Notably, those regions in our sample that show evidence of cometary, or "blister," morphology are more likely to show evidence of triggering. Keywords: HII regions -- ISM: bubbles -- Stars: formation -- Stars: protostars