The CARMA-NRO Orion Survey: The filamentary structure as seen in C18O emission

Sümeyye T. Suri, A Sanchez Monge, Peter Schilke, Seamus D. Clarke, Rowan Smith, Volker Ossenkopf-Okada, Ralf S. Klessen, Paolo Padoan, Héctor G. Arce, John Bally, John M. Carpenter, Adam Ginsberg, Doug Johnstone, Jens Kauffmann, Kong Shuo, Dariusz C. Lis, Steve Mairs, Thushara Pillai, Jaime E. Pineda, Ana Duarte-Cabral

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    Context. We present an initial overview of the filamentary structure in the Orion A molecular cloud utilizing a high angular and velocity resolution C18O(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 3-dimensional (PPV) C18O cube, we identified 625 relatively short (the longest being 1.74 pc) filaments over the entire cloud. We study 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 2 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.
    Original languageEnglish
    JournalAstronomy & Astrophysics
    Early online date21 Mar 2019
    Publication statusE-pub ahead of print - 21 Mar 2019


    • stars
    • formation – ISM
    • clouds – ISM
    • structure – ISM
    • individual objects
    • Orion A – methods
    • statistical


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