The Core Mass Function in the Orion Nebula Cluster Region: What Determines the Final Stellar Masses?

Takemura, Hideaki; Nakamura, Fúmitaka; Kong, Shuo; Arce, Héctor G.; Carpenter, John M.; Ossenkopf-Okada, Volker; Klessen, Ralf S.; Sanhueza, Patricio; Shimajiri, Yoshito; Tsukagoshi, Takashi; Kawabe, Ryohei; Ishii, Shun; Dobashi, Kazuhito; Shimoikura, Tomomi; Goldsmith, Paul F.; Sánchez-Monge, Á.; Kauffmann, Jens; Pillai, T.; Padoan, Paolo; Ginsberg, Adam; Smith, Rowan J.; Bally, John; Mairs, Steve; Pineda, Jaime E.; Lis, D. C.; Burkhart, Blakesley; Schilke, P.; Chen, Hope How-Huan; Isella, Andrea; Friesen, Rachel; Goodman, Alyssa A.; Harper, D. A.

doi:10.3847/2041-8213/abe7dd

Cited by 17 publications

(13 citation statements)

References 52 publications

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“…This picture is in agreement with competitive accretion scenarios (Bonnell et al 2001(Bonnell et al , 2004, global hierarchical collapse (Vázquez-Semadeni et al 2019), and the inertial flow model (Padoan et al 2020;Pelkonen et al 2021). Recently, Takemura et al (2021) pointed out that the cores need to accumulate gas from their surroundings to reproduce the stellar IMF from the present core mass function in the Orion Nebula Cluster region. In a different IRDC of the ASHES survey, Contreras et al (2018) estimate a core infall rate of 2 × 10 −3 M yr −1 .…”

Section: Evolutionary Stagessupporting

confidence: 81%

The ALMA Survey of 70 $μ$m Dark High-mass Clumps in Early Stages (ASHES). IV. Star formation signatures in G023.477

Morii,

Sanhueza,

Nakamura

et al. 2021

Preprint

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With a mass of ∼1000 M and a surface density of ∼0.5 g cm −2 , G023.477+0.114 also known as IRDC 18310-4 is an infrared dark cloud (IRDC) that has the potential to form high-mass stars and has been recognized as a promising prestellar clump candidate. To characterize the early stages of high-mass star formation, we have observed G023.477+0.114 as part of the ALMA Survey of 70 µm Dark Highmass Clumps in Early Stages (ASHES). We have conducted ∼1. 2 resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) at 1.3 mm in dust continuum and molecular line emission. We identified 11 cores, whose masses range from 1.1 M to 19.0 M . Ignoring magnetic fields, the virial parameters of the cores are below unity, implying that the cores are gravitationally bound. However, when magnetic fields are included, the prestellar cores are close to virial equilibrium, while the protostellar cores remain sub-virialized. Star formation activity has already started in this clump. Four collimated outflows are detected in CO and SiO. H 2 CO and CH 3 OH emission coincide with the high-velocity components seen in the CO and SiO emission. The outflows are randomly oriented for the natal filament and the magnetic field. The position-velocity diagrams suggest that episodic mass ejection has already begun even in this very early phase of protostellar formation. The masses of the identified cores are comparable to the expected maximum stellar mass that this IRDC could form (8-19 M ). We explore two possibilities on how IRDC G023.477+0.114 could eventually form high-mass stars in the context of theoretical scenarios.

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Section: Evolutionary Stagessupporting

confidence: 81%

The ALMA Survey of 70 $μ$m Dark High-mass Clumps in Early Stages (ASHES). IV. Star formation signatures in G023.477

Morii,

Sanhueza,

Nakamura

et al. 2021

Preprint

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“…This result has been consistently found through (sub)millimeter continuum observations with ground-based single-dish telescopes (e.g., Motte et al 1998;Motte & André 2001;Stanke et al 2006;Enoch et al 2008) and interferometers (e.g., Testi & Sargent 1998). It has been confirmed with deep, far-infrared to submillimeter images obtained by the Herschel space observatory (e.g., Könyves et al 2015;Benedettini et al 2018;Massi et al 2019;Ladjelate et al 2020) and a handful of near-infrared extinction maps and molecular line integrated images (Alves et al 2007;Onishi et al 2001;Takemura et al 2021). The astonishing similarity between the IMF and the observed CMFs, all of which are consistent with each other, suggests that the IMF may inherit its shape from the CMF (e.g., Motte et al 1998;André et al 2014).…”

Section: Introductionmentioning

confidence: 62%

Alma-Imf

Pouteau

Motte

Nony

et al. 2022

A&A

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Aims. The processes that determine the stellar initial mass function (IMF) and its origin are critical unsolved problems, with profound implications for many areas of astrophysics. The W43-MM2&MM3 mini-starburst ridge hosts a rich young protocluster, from which it is possible to test the current paradigm on the IMF origin. Methods. The ALMA-IMF Large Program observed the W43-MM2&MM3 ridge, whose 1.3 mm and 3 mm ALMA 12 m array continuum images reach a ~2500 au spatial resolution. We used both the best-sensitivity and the line-free ALMA-IMF images, reduced the noise with the multi-resolution segmentation technique MnGSeg, and derived the most complete and most robust core catalog possible. Using two different extraction software packages, getsf and GExt2D, we identified ~200 compact sources, whose ~100 common sources have, on average, fluxes consistent to within 30%. We filtered sources with non-negligible free-free contamination and corrected fluxes from line contamination, resulting in a W43-MM2&MM3 catalog of 205 getsf cores. With a median deconvolved FWHM size of 3400 au, core masses range from ~0.1 M⊙ to ~70 M⊙ and the getsf catalog is 90% complete down to 0.8 M⊙. Results. The high-mass end of the core mass function (CMF) of W43-MM2&MM3 is top-heavy compared to the canonical IMF. Fitting the cumulative CMF with a single power-law of the form N(> log M) ∝ Mα, we measured α = −0.95 ± 0.04, compared to the canonical α = −1.35 Salpeter IMF slope. The slope of the CMF is robust with respect to map processing, extraction software packages, and reasonable variations in the assumptions taken to estimate core masses. We explore several assumptions on how cores transfer their mass to stars (assuming a mass conversion efficiency) and subfragment (defining a core fragment mass function) to predict the IMF resulting from the W43-MM2&MM3 CMF. While core mass growth should flatten the high-mass end of the resulting IMF, core fragmentation could steepen it. Conclusions. In stark contrast to the commonly accepted paradigm, our result argues against the universality of the CMF shape. More robust functions of the star formation efficiency and core subfragmentation are required to better predict the resulting IMF, here suggested to remain top-heavy at the end of the star formation phase. If confirmed, the IMFs emerging from starburst events could inherit their top-heavy shape from their parental CMFs, challenging the IMF universality.

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“…This area was recently observed by CRAMA-NRO (Kong et al 2018). Using CARMA-NRO C 18 O (J = 1 − 0) data, Takemura et al (2021) identified approximately 200 dense cores in the filamentary region of ONC (∼1 pc −3 area), which gives a number density of n c ∼ 200 pc −3 . If we adopt r c = 0.05 pc and 〈v〉 = 1 km s −1 as representative values, we can derive the collision time τ coll ∼ 0.3 Myr using Equation (3).…”

Section: Introductionmentioning

confidence: 58%

“…If we adopt r c = 0.05 pc and 〈v〉 = 1 km s −1 as representative values, we can derive the collision time τ coll ∼ 0.3 Myr using Equation (3). Takemura et al (2021) derived the core lifetime in Orion A of ∼ 5 t ff for starless cores with densities of ρ 0 ∼ 10 4 -10 5 cm −3 , where…”

Section: Introductionmentioning

confidence: 99%

MHD Simulations of Dense Core Collision

Kinoshita

Nakamura

2022

ApJ

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We investigated the effect of magnetic fields on the collision process between dense molecular cores. We performed three-dimensional magnetohydrodynamic simulations of collisions between two self-gravitating cores using the Enzo adaptive mesh refinement code. The core was modeled as a stable isothermal Bonnor–Ebert (BE) sphere immersed in uniform magnetic fields. Collisions were characterized by the offset parameter b, Mach number of the initial core  , magnetic field strength B 0, and angle θ between the initial magnetic field and collision axis. For head-on (b = 0) collisions, one protostar was formed in the compressed layer. The higher the magnetic field strength, the lower the accretion rate. For models with b = 0 and θ = 90°, the accretion rate was more dependent on the initial magnetic field strength compared with b = 0 and θ = 0° models. For off-center (b = 1) collisions, the higher specific angular momentum increased; therefore, the gas motion was complicated. In models with b = 1 and  = 1 , the number of protostars and gas motion highly depended on B 0 and θ. For models with b = 1 and  = 3 , no significant shock-compressed layer was formed and star formation was not triggered.

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The Core Mass Function in the Orion Nebula Cluster Region: What Determines the Final Stellar Masses?

Cited by 17 publications

References 52 publications

The ALMA Survey of 70 $μ$m Dark High-mass Clumps in Early Stages (ASHES). IV. Star formation signatures in G023.477

The ALMA Survey of 70 $μ$m Dark High-mass Clumps in Early Stages (ASHES). IV. Star formation signatures in G023.477

Alma-Imf

MHD Simulations of Dense Core Collision

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