3D shape of Orion A from Gaia DR2

Author(s): Josefa E. Großschedl, João Alves, Stefan Meingast, Christine Ackerl, Joana Ascenso, Hervé Bouy, Andreas Burkert, Jan Forbrich, Verena Fürnkranz, Alyssa Goodman, Alvaro Hacar Gonzalez, Gabor Herbst-Kiss, Charles J. Lada, Irati Larreina, Kieran Leschinski, Marco Lombardi, André Moitinho, Daniel Mortimer, Eleonora Zari
Abstract: We use the Gaia DR2 distances of about 700 mid-infrared selected young stellar objects in the benchmark giant molecular cloud Orion A to infer its 3D shape and orientation. We find that Orion A is not the fairly straight filamentary cloud that we see in (2D) projection, but instead a cometary-like cloud oriented toward the Galactic plane, with two distinct components: A denser and enhanced star-forming (bent) Head, and a lower density and star-formation quieter ∼75 pc long Tail. The true extent of Orion A is not the projected ∼40 pc but ∼90 pc, making it by far the largest molecular cloud in the local neighborhood. Its aspect ratio (∼30:1) and high column-density fraction (∼45%) make it similar to large-scale Milky Way filaments ("bones"), despite its distance to the galactic mid-plane being an order of magnitude larger than typically found for these structures.
Organisation(s): Department of Astrophysics, Research Network Data Science
External organisation(s): Universidade do Porto, Université Bordeaux Montaigne, Ludwig-Maximilians-Universität München, Max-Planck-Institut für extraterrestrische Physik, University of Hertfordshire, Harvard-Smithsonian Center for Astrophysics, Università degli Studi di Milano-Bicocca, Universidade de Lisboa, University of Cambridge, Leiden University
Journal: Astronomy & Astrophysics
Volume: 619
No. of pages: 9
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/201833901
Publication date: 11-2018
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics
Keywords
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/d1c9963e-234a-4d00-a41c-bd886178daff

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