A Case Study of Triggered Star Formation in Cygnus X

TL;DR

This study investigates how radiative feedback from massive stars in Cygnus X may trigger star formation, combining new molecular line observations with archival data to analyze physical conditions and support a triggered formation scenario.

Contribution

It provides a detailed case study of triggered star formation in Cygnus X using multi-wavelength observations and compares it with the Eagle Nebula to support the triggering hypothesis.

Findings

Identification of Cyg OB2 as the ionizing source.

Detection of energetic molecular outflows.

External gas pressure dominates internal pressure.

Abstract

Radiative feedback from massive stars can potentially trigger star formation in the surrounding molecular gas. Inspired by the case of radiatively driven implosion in M16 or Eagle Nebula, we analyze a similar case of star formation observed in the Cygnus X region. We present new JCMT observations of $^{13}$CO(3-2) and C$^{18}$O(3-2) molecular lines of a cometary feature located at 50 pc north of the Cyg OB2 complex that was previously identified in $^{12}$CO(3-2) mapping. These data are combined with archival H$\alpha$, infrared, and radio continuum emission data, from which we measure the mass to be 110 M$_\odot$. We identify Cyg OB2 as the ionizing source. We measure the properties of two highly energetic molecular outflows and the photoionized rim. From this analysis, we argue the external gas pressure and gravitational energy dominate the internal pressure. The force balance along with previous simulation results and a close comparison with the case of Eagle Nebula favours a triggering scenario.