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Journal Articles Astronomy and Astrophysics - A&A Year : 2022

Gas kinematics around filamentary structures in the Orion B cloud

Jan H. Orkisz
  • Function : Author
Antoine Roueff
Antoine Marchal
  • Function : Author
François Levrier
Marc-Antoine Miville-Deschênes
Javier R. Goicoechea
  • Function : Author
Victor de Souza Magalhaes
  • Function : Author
Miriam G. Santa-Maria
Maxime Vono
Sébastien Bardeau
  • Function : Author
Pierre Chainais
  • Function : Author
Jocelyn Chanussot
  • Function : Author
Pierre Gratier
  • Function : Author
Viviana Guzman
  • Function : Author
Annie Hughes
  • Function : Author
Jouni Kainulainen
  • Function : Author
Harvey Liszt
  • Function : Author
Karin Öberg
  • Function : Author
Nicolas Peretto
  • Function : Author
Albrecht Sievers
  • Function : Author


Understanding the initial properties of star-forming material and how they affect the star formation process is key. From an observational point of view, the feedback from young high-mass stars on future star formation properties is still poorly constrained. In the framework of the IRAM 30m ORION-B large program, we obtained observations of the translucent and moderately dense gas, which we used to analyze the kinematics over a field of 5 deg^2 around the filamentary structures. We used the ROHSA algorithm to decompose and de-noise the C18O(1-0) and 13CO(1-0) signals by taking the spatial coherence of the emission into account. We produced gas column density and mean velocity maps to estimate the relative orientation of their spatial gradients. We identified three cloud velocity layers at different systemic velocities and extracted the filaments in each velocity layer. The filaments are preferentially located in regions of low centroid velocity gradients. By comparing the relative orientation between the column density and velocity gradients of each layer from the ORION-B observations and synthetic observations from 3D kinematic toy models, we distinguish two types of behavior in the dynamics around filaments: (i) radial flows perpendicular to the filament axis that can be either inflows (increasing the filament mass) or outflows and (ii) longitudinal flows along the filament axis. The former case is seen in the Orion B data, while the latter is not identified. We have also identified asymmetrical flow patterns, usually associated with filaments located at the edge of an HII region. This is the first observational study to highlight feedback from HII regions on filament formation and, thus, on star formation in the Orion B cloud. This simple statistical method can be used for any molecular cloud to obtain coherent information on the kinematics.
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Dates and versions

obspm-03994002 , version 1 (19-06-2023)



Mathilde Gaudel, Jan H. Orkisz, Maryvonne Gerin, Jérôme Pety, Antoine Roueff, et al.. Gas kinematics around filamentary structures in the Orion B cloud. Astronomy and Astrophysics - A&A, 2022, ⟨10.1051/0004-6361/202142109⟩. ⟨obspm-03994002⟩
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