The Musca molecular cloud: The perfect "filament" is still a sheet

Abstract

The true 3-dimensional (3D) morphology of the Musca molecular cloud is a topic that has received significant attention lately. Given that Musca does not exhibit intense star-formation activity, unveiling its shape has the potential of also revealing crucial information regarding the physics that dictates the formation of the first generation of stars within molecular clouds. Here, we revisit the shape of Musca and we present a comprehensive array of evidence pointing towards a shape that is extended along the line-of-sight dimension: (a) 3D maps of differential extinction; (b) new non-local thermodynamic equilibrium radiative transfer simulations of CO rotational transitions from a sheet-like, magnetically-dominated simulated cloud; (c) an effective/critical density analysis of available CO observations; (d) indirect consequences that a filamentary structure would have had, from a theoretical star-formation perspective. We conclude that the full collection of observational evidence strongly suggests that Musca has a sheet-like geometry.

arXiv comment13 pages, 14 figures. Accepted for publication in MNRAS

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Cited by in corpus (5)

• Unravelling the structure of magnetised molecular clouds with SILCC-Zoom: sheets, filaments and fragmentation
• On the 3D Curvature and Dynamics of the Musca filament
• The "C": The large Chameleon-Musca-Coalsack cloud
• CO enhancement by magnetohydrodynamic waves; Striations in the Polaris Flare
• Loose threads: parsec-scale filamentation in the high Galactic latitude molecular clouds MBM 3 and MBM 16