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Mapping Physical Parameters in Orion KL at High Spatial Resolution

Wilkins, Olivia H. and Carroll, P. Brandon and Blake, Geoffrey A. (2022) Mapping Physical Parameters in Orion KL at High Spatial Resolution. Astrophysical Journal, 924 (1). Art. No. 4. ISSN 0004-637X. doi:10.3847/1538-4357/ac3132.

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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 of ¹³CH₃OH ν = 0 (∼0farcs3 and ∼0farcs7) and CH₃CN ν₈ = 1 (∼0farcs2 and ∼0farcs9) 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 0farcs2 beam than in a 0farcs9 beam, indicative of possible internal sources of heating. Furthermore, the velocity field includes a bipolar ∼7–8 km s⁻¹ feature with a southeast–northwest orientation against the surrounding ∼4–5 km s⁻¹ velocity 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 the (hidden) sources of luminosity and heating within Orion KL are necessary to better understand the nebula and its chemistry.

Item Type:Article
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URLURL TypeDescription Paper
Wilkins, Olivia H.0000-0001-7794-7639
Carroll, P. Brandon0000-0002-3191-5401
Blake, Geoffrey A.0000-0003-0787-1610
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 August 12; revised 2021 October 15; accepted 2021 October 18; published 2022 January 4. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2017.1.01149, ADS/JAO.ALMA#2016.1.01019, and ADS/JAO.ALMA#2013.1.01034. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. The National Radio Astronomy Observatory (NRAO) is a facility of the National Science Foundation (NSF) operated under Associated Universities, Inc. (AUI). This research made use of APLpy, an open-source plotting package for Python (Robitaille & Bressert 2012; Robitaille 2019). This work has been supported by the NSF Graduate Research Fellowship Program under grant No. DGE-1144469 and NRAO Student Observing Support under Award No. SOSPA6-014. O.H.W. is additionally supported by an ARCS Los Angeles Founder Chapter scholarship. G.A.B. gratefully acknowledges support from the NSF AAG (AST-1514918) and NASA Astrobiology (NNX15AT33A) and Exoplanet Research (XRP, NNX16AB48G) programs. This work benefited from discussions with Cam Buzard, Dana Anderson, Griffin Mead, Kyle Virgil, and Sadie Dutton. The authors thank Susanna Widicus Weaver and the anonymous referee for feedback on the prepared manuscript, as well as Adam Ginsburg and Justin Otter for comments related to the nature of the Hot Core. O.H.W. thanks Erica Keller, Sarah Wood, and the NRAO North American ALMA Science Center (NAASC) for their assistance with the data reduction. O.H.W. also thanks the custodial staff at Caltech, especially Cruz Martinez. Facility: ALMA - Atacama Large Millimeter Array. Software: CASA (McMullin et al. 2007), CDMS (Müller et al. 2001), LMFIT (Newville et al. 2019), APLpy (Robitaille & Bressert 2012; Robitaille 2019), Gaussian16 (Frisch et al.2016).
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1144469
National Radio Astronomy ObservatorySOSPA6-014
Subject Keywords:Astrochemistry; Interstellar medium; Nebulae; Astrosphere interstellar medium interactions; Interferometry
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Astrochemistry (75); Interstellar medium (847); Nebulae (1095); Astrosphere interstellar medium interactions (106); Interferometry (808)
Record Number:CaltechAUTHORS:20220114-265221000
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Official Citation:Olivia H. Wilkins et al 2022 ApJ 924 4
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112926
Deposited By: George Porter
Deposited On:18 Jan 2022 16:44
Last Modified:18 Jan 2022 16:44

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