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FilDReaMS: II. Application to the analysis of the relative orientations between filaments and the magnetic field in four Herschel fields
Context. Both simulations and observations of the interstellar medium show that the study of the relative orientations between filamentary structures and the magnetic field can bring new insight into the role played by magnetic fields in the formation and evolution of filaments and in the process of...
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Published in: | Astronomy and astrophysics (Berlin) 2022-12, Vol.668, p.A42 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites |
Online Access: | Get full text |
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Summary: | Context.
Both simulations and observations of the interstellar medium show that the study of the relative orientations between filamentary structures and the magnetic field can bring new insight into the role played by magnetic fields in the formation and evolution of filaments and in the process of star formation.
Aims.
We provide a first application of
FilDReaMS
, the new method presented in the companion paper to detect and analyze filaments in a given image. The method relies on a template that has the shape of a rectangular bar with variable width. Our goal is to investigate the relative orientations between the detected filaments and the magnetic field.
Methods.
We apply
FilDReaMS
to a small sample of four
Herschel
fields (G210, G300, G82, G202) characterized by different Galactic environments and different evolutionary stages. First, we look for the most prevalent bar widths, and we examine the networks formed by filaments of different bar widths as well as their hierarchical organization. Second, we compare the filament orientations to the magnetic field orientation inferred from
Planck
polarization data and, for the first time, we study the statistics of the relative orientation angle as functions of both spatial scale and H
2
column density.
Results.
We find preferential relative orientations in the four
Herschel
fields: small filaments with low column densities tend to be slightly more parallel than perpendicular to the magnetic field; in contrast, large filaments, which all have higher column densities, are oriented nearly perpendicular (or, in the case of G202, more nearly parallel) to the magnetic field. In the two nearby fields (G210 and G300), we observe a transition from mostly parallel to mostly perpendicular relative orientations at an H
2
column density ≃ 1.1 × 10
21
cm
−2
and 1.4 × 10
21
cm
−2
, respectively, consistent with the results of previous studies.
Conclusions.
Our results confirm the existence of a coupling between magnetic fields at cloud scales and filaments at smaller scale. They also illustrate the potential of combining
Herschel
and
Planck
observations, and they call for further statistical analyses with our dedicated method. |
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ISSN: | 0004-6361 1432-0746 |
DOI: | 10.1051/0004-6361/202244550 |