Interstellar Plunging Waves: ALMA Resolves the Physical Structure of Nonstationary MHD Shocks
Date Issued
2019
Author(s)
Cosentino, Giuliana
•
Jiménez-Serra, Izaskun
•
Caselli, Paola
•
Henshaw, Jonathan D.
•
Barnes, Ashley T.
•
Tan, Jonathan C.
•
•
•
Wu, Benjamin
Abstract
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.
Volume
881
Issue
2
Start page
L42
Issn Identifier
2041-8205
Ads BibCode
2019ApJ...881L..42C
Rights
open.access
File(s)![Thumbnail Image]()
![Thumbnail Image]()
Loading...
Name
1908.09743.pdf
Description
preprint
Size
2.68 MB
Format
Adobe PDF
Checksum (MD5)
442c1cba9de6e6f2dddea5b0d64cf0b0
Loading...
Name
Cosentino_2019_ApJL_881_L42.pdf
Description
pdf editoriale
Size
1023.5 KB
Format
Adobe PDF
Checksum (MD5)
698fcb778079a081c11fa9ea4f983cdf