Magnetically dominated parallel interstellar filaments in the infrared dark cloud G14.225-0.506
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Universidade Federal de Minas Gerais
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Artigo de periódico
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The infrared dark cloud G14.225-0.506 (IRDC G14.2) displays a remarkable complex of parallel dense molecular filaments projected on the plane of the sky. Previous studies of dust emission and molecular lines have speculated
whether magnetic fields could have played an important role in the formation of such elongated structures, which
are hosts to numerous young stellar sources. In this work we have conducted a vast polarimetric survey at optical
and near-infrared wavelengths in order to study the morphology of magnetic field lines in IRDC G14.2 through the
observation of background stars. The orientation of interstellar polarization, which traces magnetic field lines, is perpendicular to most of the filamentary features within the cloud. Additionally, the larger-scale molecular cloud as a whole exhibits an elongated shape also perpendicular to magnetic fields. Estimates of magnetic field strengths indicate values in the range 320–550 μG, which allow sub-alfvénic conditions, but do not prevent the gravitational collapse of hub–filament structures, which in general are close to the critical state. These characteristics suggest
that magnetic fields played the main role in regulating the collapse from large to small scales, leading to the
formation of series of parallel elongated structures. The morphology is also consistent with numerical simulations
that show how gravitational instabilities develop when subjected to strong magnetic fields. Finally, the results
corroborate the hypothesis that strong support from internal magnetic fields might explain why the cloud seems to
be contracting on a timescale 2–3 times longer than what is expected from a free-fall collapse.
Abstract
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Campos magnéticos, Polarimetria, Meio interestelar
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Stars
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https://iopscience.iop.org/article/10.3847/0004-637X/832/2/186