3D shape of Orion A from Gaia DR2
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.
Item Type | Article |
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Additional information | Reproduced with permission from Astronomy & Astrophysics. © 2018 ESO. |
Keywords | local insterstellar matter, methods: observational, methods: statistical, parallaxes, stars: distances, stars: formation, astronomy and astrophysics, space and planetary science |
Date Deposited | 15 May 2025 13:52 |
Last Modified | 01 Jun 2025 21:12 |
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picture_as_pdf - 1808.05952v1.pdf
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