Issue |
A&A
Volume 590, June 2016
|
|
---|---|---|
Article Number | A110 | |
Number of page(s) | 8 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/201527068 | |
Published online | 24 May 2016 |
Filamentary structure and magnetic field orientation in Musca⋆
1
Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, bus
2401,
3001
Leuven,
Belgium
e-mail: nick.cox@irap.omp.eu
2
Institut d’Astrophysique Spatiale, CNRS (UMR 8617) Université
Paris-Sud 11, Bâtiment
121, Orsay,
France
3
Laboratoire AIM Paris, Saclay, CEA/DSM, CNRS, Université Paris
Diderot, IRFU, Service
d’Astrophysique, Centre d’Études de Saclay, Orme des Merisiers,
91191
Gif-sur-Yvette,
France
4
ESA, Directorate of Science, Scientific Support Office, European
Space Research and Technology Centre (ESTEC/SCI-S), Keplerlaan 1,
2201 AZ
Noordwijk, The
Netherlands
5
Konkoly Observatory, Research Centre for Astronomy and Earth
Sciences, Hungarian Academy of Sciences, PO Box 67, 1525
Budapest,
Hungary
6
Department of Astronomy, Boston University,
725 Commonwealth Avenue,
Boston, MA
02215,
USA
7
Université de Toulouse, UPS-OMP, IRAP, 31028
Toulouse,
France
8
Centre d’Étude Spatiale des Rayonnements, IRAP, 9 Av. colonel
Roche, BP 44346, 31028
Toulouse,
France
9
OASU/LAB Univ. Bordeaux, CNRS, UMR 5804,
33270
Floirac,
France
10
I. Physik. Institut, University of Cologne,
50937
Cologne,
Germany
11
European Space Agency (ESA/ESAC), PO Box 78, 28691 Villanueva de la Cañada,
Madrid,
Spain
12
European Space Agency (ESA), 3700 San Martin Dr,
Baltimore, MD
21218,
USA
Received: 27 July 2015
Accepted: 26 February 2016
Herschel has shown that filamentary structures are ubiquitous in star-forming regions, in particular in nearby molecular clouds associated with Gould’s Belt. High dynamic range far-infrared imaging of the Musca cloud with SPIRE and PACS reveals at least two types of filamentary structures: (1) the main ~10-pc scale high column-density linear filament; and (2) low column-density striations in close proximity to the main filament. In addition, we find features with intermediate column densities (hair-like strands) that appear physically connected to the main filament. We present an analysis of this filamentary network traced by Herschel and explore its connection with the local magnetic field. We find that both the faint dust emission striations and the plane-of-the-sky (POS) magnetic field are locally oriented close to perpendicular to the high-density main filament (position angle ~25−35°). The low-density striations and strands are oriented parallel to the POS magnetic field lines, which are derived previously from optical polarization measurements of background stars and more recently from Planck observations of dust polarized emission. The position angles are 97 ± 25°, 105 ± 7°, and 105 ± 5°. From these observations, we propose a scenario in which local interstellar material in this cloud has condensed into a gravitationally-unstable filament (with “supercritical” mass per unit length) that is accreting background matter along field lines through the striations. We also compare the filamentary structure in Musca with what is seen in similar Herschel observations of the Taurus B211/3 filament system and find that there is significantly less substructure in the Musca main filament than in the B211/3 filament. We suggest that the Musca cloud may represent an earlier evolutionary stage in which the main filament has not yet accreted sufficient mass and energy to develop a multiple system of intertwined filamentary components.
Key words: ISM: individual objects: Musca / ISM: structure / ISM: clouds / stars: formation / infrared: ISM
© ESO, 2016
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