Focusing MHD Wave as a Trigger of Star Formation

TL;DR

This paper models how focusing fast-mode MHD waves in interstellar space can trigger star formation by compressing molecular clouds at focal points, supported by simulations and application to regions M16 and M17.

Contribution

It introduces the Focusing MHD Wave model, demonstrating wave convergence as a mechanism for triggered star formation, with simulations and real-region applications.

Findings

MHD waves can be trapped and focused onto molecular clouds.

Focusing waves induce implosive compression leading to star formation.

Application to M16 and M17 supports the model's validity.

Abstract

Propagation of fast-mode magnetohydrodynamic (MHD) waves in the interstellar space is simulated, and focusing MHD wave (FMW) model is proposed for triggered star formation (SF). Waves from an SF region are trapped by nearby molecular clouds and converge onto their focal points, causing implosive compression. Even an isolated cloud suffers from long-distance invasion of waves from remote sources. Echoing SF occurs inside a cloud as well as between clouds. Repetitive refocusing in a filamentary cloud suggests spatial periodicity in SF sites along the filament. The model is applied to the SF regions M16 and M17, where MHD waves produced by M16 are shown to converge onto the focal point of nearby GMC and trigger the SF in M17.