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Published March 2019 | Published
Journal Article Open

CARMA-NRO Orion Survey. Filamentary structure as seen in C^(18)O emission


Context. We present an initial overview of the filamentary structure in the Orion A molecular cloud utilizing a high angular and velocity resolution C^(18)O(1–0) emission map that was recently produced as part of the CARMA-NRO Orion Survey. Aims. The main goal of this study is to build a credible method to study varying widths of filaments which has previously been linked to star formation in molecular clouds. Due to the diverse star forming activities taking place throughout its ~20 pc length, together with its proximity of 388 pc, the Orion A molecular cloud provides an excellent laboratory for such an experiment to be carried out with high resolution and high sensitivity. Methods. Using the widely-known structure identification algorithm, DisPerSE, on a three-dimensional (PPV) C18O cube, we identify 625 relatively short (the longest being 1.74 pc) filaments over the entire cloud. We studied the distribution of filament widths using FilChaP, a python package that we have developed and made publicly available. Results. We find that the filaments identified in a two square-degree PPV cube do not overlap spatially, except for the complex OMC-4 region that shows distinct velocity components along the line of sight. The filament widths vary between 0.02 and 0.3 pc depending on the amount of substructure that a filament possesses. The more substructure a filament has, the larger is its width. We also find that despite this variation, the filament width shows no anticorrelation with the central column density which is in agreement with previous Herschel observations.

Additional Information

© 2019 ESO. Article published by EDP Sciences. Received 8 August 2018; Accepted 2 January 2019; Published online 21 March 2019. We thank the referee for their insightful comments that helped improve this manuscript and FilChaP. S.S., A.S.M., P.S. and V.O.O. acknowledge funding by the Deutsche Forschungsgemeinschaft (DFG) via the Sonderforschungsbereich SFB 956 Conditions and Impact of Star Formation (subprojects A4, A6, C1, and C3) and the Bonn-Cologne Graduate School. S.D.C. acknowledges support from the ERC starting grant No. 679852 RADFEEDBACK. R.J.S. gratefully acknowledges support from an STFC Ernest Rutherford fellowship. This research was carried out in part at the Jet Propulsion Laboratory which is operated for NASA by the California Institute of Technology. P.P. acknowledges support by the Spanish MINECO under project AYA2017-88754-P (AEI/FEDER,UE). H.G.A. and S.K. acknowledge support from the National Science Foundation through grant AST-1140063. H.G.A. and S.K. acknowledge support from the National Science Foundation through grant AST-1140063. Software: astropy (Price-Whelan et al. 2018), matplotlib (Hunter 2007), scipy (Jones et al. 2001), pandas (McKinney 2010), APLpy (Robitaille & Bressert 2012).

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August 19, 2023
October 20, 2023