MAGNETICALLY DOMINATED PARALLEL INTERSTELLAR FILAMENTS IN THE INFRARED DARK CLOUD G14.225-0.506

Journal Article · Thu Dec 01 04:00:00 EST 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/832/2/186· OSTI ID:22660994

Santos, Fábio P. ^[1]; Busquet, Gemma; Girart, Josep Miquel ^[2]; Franco, Gabriel A. P. ^[3]; Zhang, Qizhou ^[4]

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1. Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)
2. Institut de Ciències de l’Espai (CSIC-IEEC), Campus UAB, Carrer de Can Magrans, S/N E-08193 Bellaterra, Catalunya (Spain)
3. Departamento de Física—ICEx—UFMG, Caixa Postal 702, 30.123-970 Belo Horizonte, MG (Brazil)
4. Harvard-Smithsonian Center for Astrophysics, 60, Garden Street, Cambridge, MA 02138 (United States)

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 μ G, 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.

• OSTI ID: 22660994
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 832; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ALFVEN WAVES
CLOUDS
COMPUTERIZED SIMULATION
COSMIC DUST
FILAMENTS
GRAVITATIONAL COLLAPSE
MORPHOLOGY
ORIENTATION
POLARIZATION
SKY
STARS
WAVELENGTHS