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1. CARMA-NRO Orion Survey: Unbiased Survey of Dense Cores and Core Mass Functions in Orion A

   https://doi.org/10.3847/1538-4365/aca4d4  

   Takemura, Hideaki ; Nakamura, Fumitaka ; Arce, Héctor G. ; Schneider, Nicola ; Ossenkopf-Okada, Volker ; Kong, Shuo ; Ishii, Shun ; Dobashi, Kazuhito ; Shimoikura, Tomomi ; Sanhueza, Patricio ; et al ( January 2023 , The Astrophysical Journal Supplement Series)

   Abstract The mass distribution of dense cores is a potential key to understanding the process of star formation. Applying dendrogram analysis to the CARMA-NRO Orion C 18 O ( J = 1–0) data, we identify 2342 dense cores, about 22% of which have virial ratios smaller than 2 and can be classified as gravitationally bound cores. The derived core mass function (CMF) for bound starless cores that are not associate with protostars has a slope similar to Salpeter’s initial mass function (IMF) for the mass range above 1 M ⊙ , with a peak at ∼0.1 M ⊙ . We divide the cloud into four parts based on decl., OMC-1/2/3, OMC-4/5, L1641N/V380 Ori, and L1641C, and derive the CMFs in these regions. We find that starless cores with masses greater than 10 M ⊙ exist only in OMC-1/2/3, whereas the CMFs in OMC-4/5, L1641N, and L1641C are truncated at around 5–10 M ⊙ . From the number ratio of bound starless cores and Class II objects in each subregion, the lifetime of bound starless cores is estimated to be 5–30 freefall times, consistent with previous studies for other regions. In addition, we discuss core growth by mass accretion from the surrounding cloud material to explain the coincidence of peak masses between IMFs and CMFs. The mass accretion rate required for doubling the core mass within a core lifetime is larger than that of Bondi–Hoyle accretion by a factor of order 2. This implies that more dynamical accretion processes are required to grow cores. 

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2. Deciphering the 3D Orion Nebula-IV: The HH 269 Flow Emerges from the Orion-S Embedded Molecular Cloud

   https://doi.org/10.3847/1538-4357/abe1b0  

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

   null (Ed.)
3. Observations of the Orion Source I Disk and Outflow Interface

   https://doi.org/10.3847/1538-4357/ab5864  

   Wright, Melvyn ; Plambeck, Richard ; Hirota, Tomoya ; Ginsburg, Adam ; McGuire, Brett ; Bally, John ; Goddi, Ciriaco ( February 2020 , The Astrophysical Journal)

   null (Ed.)
4. The TEMPO Survey. I. Predicting Yields of Transiting Exosatellites, Moons, and Planets from a 30 days Survey of Orion with the Roman Space Telescope

   https://doi.org/10.1088/1538-3873/acafa4  

   Limbach, Mary Anne ; Soares-Furtado, Melinda ; Vanderburg, Andrew ; Best, William M. ; Cody, Ann Marie ; D’Onghia, Elena ; Heller, René ; Hensley, Brandon S. ; Kounkel, Marina ; Kraus, Adam ; et al ( January 2023 , Publications of the Astronomical Society of the Pacific)

   Abstract We present design considerations for the Transiting Exosatellites, Moons, and Planets in Orion (TEMPO) Survey with the Nancy Grace Roman Space Telescope. This proposed 30 days survey is designed to detect a population of transiting extrasolar satellites, moons, and planets in the Orion Nebula Cluster (ONC). The young (1–3 Myr), densely populated ONC harbors about a thousand bright brown dwarfs (BDs) and free-floating planetary-mass objects (FFPs). TEMPO offers sufficient photometric precision to monitor FFPs with M >1 M J for transiting satellites. The survey is also capable of detecting FFPs down to sub-Saturn masses via direct imaging, although follow-up confirmation will be challenging. TEMPO yield estimates include 14 (3–22) exomoons/satellites transiting FFPs and 54 (8–100) satellites transiting BDs. Of this population, approximately 50% of companions would be “super-Titans” (Titan to Earth mass). Yield estimates also include approximately 150 exoplanets transiting young Orion stars, of which >50% will orbit mid-to-late M dwarfs. TEMPO would provide the first census demographics of small exosatellites orbiting FFPs and BDs, while simultaneously offering insights into exoplanet evolution at the earliest stages. This detected exosatellite population is likely to be markedly different from the current census of exoplanets with similar masses (e.g., Earth-mass exosatellites that still possess H/He envelopes). Although our yield estimates are highly uncertain, as there are no known exoplanets or exomoons analogous to these satellites, the TEMPO survey would test the prevailing theories of exosatellite formation and evolution, which limit the certainty surrounding detection yields. 

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5. Detection of Irregular, Submillimeter Opaque Structures in the Orion Molecular Clouds: Protostars within 10,000 yr of Formation?

   https://doi.org/10.3847/1538-4357/ab659e  

   Karnath, N. ; Megeath, S. T. ; Tobin, J. J. ; Stutz, A. ; Li, Z.-Y. ; Sheehan, P. ; Reynolds, N. ; Sadavoy, S. ; Stephens, I. W. ; Osorio, M. ; et al ( February 2020 , The Astrophysical Journal)