Gas kinematics around filamentary structures in the Orion B cloud by Mathilde Gaudel et al. on Tuesday 29 November

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.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.14350v1