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Title: Mapping Physical Parameters in Orion KL at High Spatial Resolution

The Orion Kleinmann-Low nebula (Orion KL) is notoriously complex and exhibits a range of physical and chemical components. We conducted high-angular-resolution (subarcsecond) observations of13CH3OHν= 0 (∼0.″3 and ∼0.″7) and CH3CNν8= 1 (∼0.″2 and ∼0.″9) line emission with the Atacama Large Millimeter/submillimeter Array (ALMA) to investigate Orion KL’s structure on small spatial scales (≤350 au). Gas kinematics, excitation temperatures, and column densities were derived from the molecular emission via a pixel-by-pixel spectral line fitting of the image cubes, enabling us to examine the small-scale variation of these parameters. Subregions of the Hot Core have a higher excitation temperature in a 0.″2 beam than in a 0.″9 beam, indicative of possible internal sources of heating. Furthermore, the velocity field includes a bipolar ∼7–8 km s−1feature with a southeast–northwest orientation against the surrounding ∼4–5 km s−1velocity field, which may be due to an outflow. We also find evidence of a possible source of internal heating toward the Northwest Clump, since the excitation temperature there is higher in a smaller beam versus a larger beam. Finally, the region southwest of the Hot Core (Hot Core-SW) presents itself as a particularly heterogeneous region bridging the Hot Core and Compact Ridge. Additional studies to identify more » the (hidden) sources of luminosity and heating within Orion KL are necessary to better understand the nebula and its chemistry.

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Publication Date:
Journal Name:
The Astrophysical Journal
Page Range or eLocation-ID:
Article No. 4
DOI PREFIX: 10.3847
Sponsoring Org:
National Science Foundation
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