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1. Deciphering the 3D Orion Nebula. III. Structure on the NE Boundary of the Orion-S Embedded Molecular Cloud

   https://doi.org/10.3847/1538-4357/abd856  

   O’Dell, C. R. ; Abel, N. P. ; Ferland, G. J. ( February 2021 , The Astrophysical Journal)

   null (Ed.)
2. Stellar Proper Motions in the Orion Nebula Cluster

   https://doi.org/10.3847/1538-3881/aafb09  

   Kim, Dongwon ; Lu, Jessica R. ; Konopacky, Quinn ; Chu, Laurie ; Toller, Elizabeth ; Anderson, Jay ; Theissen, Christopher A. ; Morris, Mark R. ( March 2019 , The Astronomical Journal)
3. Structure of the Source I Disk in Orion-KL

   https://doi.org/10.3847/1538-4357/ac391b  

   Wright, Melvyn ; Bally, John ; Hirota, Tomoya ; Miller, Kyle ; Harding, Tyler ; Colleluori, Keira ; Ginsburg, Adam ; Goddi, Ciriaco ; McGuire, Brett ( January 2022 , The Astrophysical Journal)

   Abstract This paper analyses images from 43 to 340 GHz to trace the structure of the Source I (SrcI) disk in Orion-KL with ∼12 au resolution. The data reveal an almost edge-on disk with an outside diameter ∼100 au, which is heated from the inside. The high opacity at 220–340 GHz hides the internal structure and presents a surface temperature ∼500 K. Images at 43, 86 and 99 GHz reveal structure within the disk. At 43 GHz there is bright compact emission with brightness temperature ∼1300 K. Another feature, most prominent at 99 GHz, is a warped ridge of emission. The data can be explained by a simple model with a hot inner structure, seen through cooler material. A wide-angle outflow mapped in SiO emission ablates material from the interior of the disk, and extends in a bipolar outflow over 1000 au along the rotation axis of the disk. SiO v = 0, J = 5–4 emission appears to have a localized footprint in the warped ridge. These observations suggest that the ridge is the working surface of the disk, and heated by accretion and the outflow. The disk structure may be evolving, with multiple accretion and outflow events. We discuss two sources of variability: (1) variable accretion onto the disk as SrcI travels through the filamentary debris from the Becklin–Neugebauer Object-SrcI encounter ∼550 yr ago; and (2) episodic accretion from the disk onto the protostar, which may trigger multiple outflows. The warped inner-disk structure is direct evidence that SrcI could be a binary experiencing episodic accretion. 

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4. Mapping dust in the giant molecular cloud Orion A

   https://doi.org/10.1093/mnras/stae268  

   Gration, Amery ; Magorrian, John ( January 2024 , Monthly Notices of the Royal Astronomical Society)

   The Sun is located close to the Galactic mid-plane, meaning that we observe the Galaxy through significant quantities of dust. Moreover, the vast majority of the Galaxy’s stars also lie in the disc, meaning that dust has an enormous impact on the massive astrometric, photometric and spectroscopic surveys of the Galaxy that are currently underway. To exploit the data from these surveys we require good three-dimensional maps of the Galaxy’s dust. We present a new method for making such maps in which we form the best linear unbiased predictor of the extinction at an arbitrary point based on the extinctions for a set of observed stars. This method allows us to avoid the artificial inhomogeneities (so-called ‘fingers of God’) and resolution limits that are characteristic of many published dust maps. Moreover, it requires minimal assumptions about the statistical properties of the interstellar medium. In fact, we require only a model of the first and second moments of the dust density field. The method is suitable for use with directly measured extinctions, such as those provided by the Rayleigh–Jeans colour excess method, and inferred extinctions, such as those provided by hierarchical Bayesian models like StarHorse. We test our method by mapping dust in the region of the giant molecular cloud Orion A. Our results indicate a foreground dust cloud at a distance of 350 pc, which has been identified in work by another author.

    

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5. The Radcliffe wave as the gas spine of the Orion arm

   https://doi.org/10.1051/0004-6361/202243761  

   Swiggum, C. ; Alves, J. ; D’Onghia, E. ; Benjamin, R. A. ; Thulasidharan, L. ; Zucker, C. ; Poggio, E. ; Drimmel, R. ; Gallagher III, J. S. ; Goodman, A. ( August 2022 , Astronomy & Astrophysics)

   The Radcliffe wave is a ∼3 kpc long coherent gas structure containing most of the star-forming complexes near the Sun. In this Letter we aim to find a Galactic context for the Radcliffe wave by looking into a possible relationship between the gas structure and the Orion (local) arm. We use catalogs of massive stars and young open clusters based on Gaia Early Data Release 3 (EDR3) astrometry, in conjunction with kiloparsec-scale 3D dust maps, to investigate the Galactic XY spatial distributions of gas and young stars. We find a quasi-parallel offset between the luminous blue stars and the Radcliffe wave, in that massive stars and clusters are found essentially inside and downstream from the Radcliffe wave. We examine this offset in the context of color gradients observed in the spiral arms of external galaxies, where the interplay between density wave theory, spiral shocks, and triggered star formation has been used to interpret this particular arrangement of gas and dust as well as OB stars, and outline other potential explanations as well. We hypothesize that the Radcliffe wave constitutes the gas reservoir of the Orion (local) arm, and that it presents itself as a prime laboratory to study the interface between Galactic structure, the formation of molecular clouds in the Milky Way, and star formation. 

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