Interstellar Plunging Waves: ALMA Resolves the Physical Structure of Nonstationary MHD Shocks
Artikel i vetenskaplig tidskrift, 2019

Magnetohydrodynamic (MHD) shocks are violent events that inject large amounts of energy in the interstellar medium dramatically modifying its physical properties and chemical composition. Indirect evidence for the presence of such shocks has been reported from the especial chemistry detected toward a variety of astrophysical shocked environments. However, the internal physical structure of these shocks remains unresolved since their expected spatial scales are too small to be measured with current instrumentation. Here we report the first detection of a fully spatially resolved, MHD shock toward the infrared dark cloud (IRDC) G034.77-00.55. The shock, probed by silicon monoxide (SiO) and observed with the Atacama Large Millimeter/submillimeter Array (ALMA), is associated with the collision between the dense molecular gas of the cloud and a molecular gas flow pushed toward the IRDC by the nearby supernova remnant (SNR) W44. The interaction is occurring on subparsec spatial scales thanks to the enhanced magnetic field of the SNR, making the dissipation region of the MHD shock large enough to be resolved with ALMA. Our observations suggest that molecular flow-flow collisions can be triggered by stellar feedback, inducing shocked molecular gas densities compatible with those required for massive star formation.

ISM: molecules

shock waves

ISM: clouds (G034.77-00.55)

ISM: supernova remnants (W44)


Giuliana Cosentino

European Southern Observatory Santiago

University College London (UCL)

Izaskun Jimenez-Serra

Queen Mary University of London

Centro de Astrobiología (INTA-CSIC)

Paola Caselli


Jonathan D. Henshaw


Ashley T. Barnes

Argelander-Institut für Astronomie

Jonathan Tan

University of Virginia

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Galaktisk astrofysik

Serena Viti

University College London (UCL)

Francesco Fontani

Osservatorio Astrofisico di Arcetri

Benjamin Wu

National Astronomical Observatory of Japan

Astrophysical Journal Letters

2041-8205 (ISSN) 2041-8213 (eISSN)

Vol. 881 2 L42


Astronomi, astrofysik och kosmologi

Atom- och molekylfysik och optik

Fusion, plasma och rymdfysik



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