An ALMA View of Molecular Filaments in the Large Magellanic Cloud. II. An Early Stage of High-mass Star Formation Embedded at Colliding Clouds in N159W-South

Tokuda, Kazuki; Fukui, Y.; Harada, Ryohei; Saigo, Kazuya; Tachihara, Kengo; Tsuge, Kisetsu; Inoue, Tsuyoshi; Torii, Kazufumi; Nishimura, Atsushi; Zahorecz, Sarolta; Nayak, Omnarayani; Meixner, Margaret; Minamidani, Tetsuhiro; Kawamura, Akiko; Mizuno, N.; Indebetouw, R.; Sewiło, M.; Madden, S.; Galametz, M.; Lebouteiller, V.; Chen, C.-H. Rosie; Onishi, Toshikazu

doi:10.3847/1538-4357/ab48ff

Cited by 66 publications

(45 citation statements)

References 78 publications

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“…In models v12GyTn and v12GyTy, most of the line-masses are sub-critical at t t fil (panels (e) and (g) in Figure 11), but they quickly evolve into supercritical ones by continuous accretion flows induced by the oblique shock in roughly 1 Myr (panels (f) and (h) in Figure 11). Recent observations suggest that high line-mass filaments greater than 100 M pc −1 are strong candidates for massive star progenitors (Fukui et al 2019;Shimajiri et al 2019;Tokuda et al 2019). We stress that such high line-mass filaments are naturally created in high shock velocity models in a short time.…”

Section: Filament Line Mass Functionmentioning

confidence: 72%

Classification of Filament Formation Mechanisms in Magnetized Molecular Clouds

Abe

Inoue

Inutsuka

et al. 2021

ApJ

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Recent observations of molecular clouds show that dense filaments are the sites of present-day star formation. Thus, it is necessary to understand the filament formation process because these filaments provide the initial condition for star formation. Theoretical research suggests that shock waves in molecular clouds trigger filament formation. Since several different mechanisms have been proposed for filament formation, the formation mechanism of the observed star-forming filaments requires clarification. In the present study, we perform a series of isothermal magnetohydrodynamics simulations of filament formation. We focus on the influences of shock velocity and turbulence on the formation mechanism and identified three different mechanisms for the filament formation. The results indicate that when the shock is fast, at shock velocity v sh ≃ 7 km s−1, the gas flows driven by the curved shock wave create filaments irrespective of the presence of turbulence and self-gravity. However, at a slow shock velocity v sh ≃ 2.5 km s−1, the compressive flow component involved in the initial turbulence induces filament formation. When both the shock velocities and turbulence are low, the self-gravity in the shock-compressed sheet becomes important for filament formation. Moreover, we analyzed the line-mass distribution of the filaments and showed that strong shock waves can naturally create high-line-mass filaments such as those observed in the massive star-forming regions in a short time. We conclude that the dominant filament formation mode changes with the velocity of the shock wave triggering the filament formation.

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Section: Filament Line Mass Functionmentioning

confidence: 72%

Classification of Filament Formation Mechanisms in Magnetized Molecular Clouds

Abe

Inoue

Inutsuka

et al. 2021

ApJ

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“…Therefore, the surface brightness maps of CO lines can be a tool to understand the physical properties of star-forming clouds. The CO observations in the low-metallicity galaxies (such as LMC/SMC) are progressing (e.g., Fukui et al 2015;Muraoka et al 2017;Tokuda et al 2019). We plan to model the CO map to compare with the observations in a future study.…”

Section: Summary and Discussionmentioning

confidence: 99%

Radiation hydrodynamics simulations of massive star cluster formation in giant molecular clouds

Fukushima,

Yajima

2021

Preprint

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By performing three-dimensional radiation hydrodynamics simulations, we study the formation of young massive star clusters (YMCs, 𝑀 * > 10 4 𝑀 ) in clouds with the surface density ranging from Σ cl = 80 to 3200 𝑀 pc −2 . We find that photoionization feedback suppresses star formation significantly in clouds with low surface density. Once the initial surface density exceeds ∼ 100 𝑀 pc −2 for clouds with 𝑀 cl = 10 6 𝑀 and 𝑍 = 𝑍 , most of the gas is converted into stars because the photoionization feedback is inefficient in deep gravitational potential. In this case, the star clusters are massive and gravitationally bounded as YMCs. The transition surface density increases as metallicity decreases, and it is ∼ 350 𝑀 pc −2 for 𝑍 = 10 −2 𝑍 . We show that more than 10 percent of star-formation efficiency (SFE) is needed to keep a star cluster gravitationally bounded even after the disruption of a cloud. Also, we develop a semi-analytical model reproducing the SFEs obtained in our simulations. We find that the SFEs are fit with a power-law function with the dependency ∝ Σ 1/2 cl for low-surface density and rapidly increases at the transition surface densities. The conditions of the surface density and the metallicity match recent observations of giant molecular clouds forming YMCs in nearby galaxies.

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“…Myers 2009;Kirk et al 2013), to high-mass starforming regions (e.g. Peretto et al 2013;Schwörer et al 2019), and have even been observed in our closest neighbouring galaxy (Fukui et al 2019;Tokuda et al 2019). The formation mechanism of such hubs is not yet fully understood (see Myers 2009, for a description of possible mechanisms).…”

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confidence: 91%

An ALMA study of hub-filament systems – I. On the clump mass concentration within the most massive cores

Anderson

Peretto

Ragan

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The physical processes behind the transfer of mass from parsec-scale clumps to massive-star-forming cores remain elusive. We investigate the relation between the clump morphology and the mass fraction that ends up in its most massive core (MMC) as a function of infrared brightness, i.e. a clump evolutionary tracer. Using ALMA 12 m and ACA we surveyed 6 infrared-dark hubs in 2.9 mm continuum at ∼3″ resolution. To put our sample into context, we also re-analysed published ALMA data from a sample of 29 high mass-surface density ATLASGAL sources. We characterise the size, mass, morphology, and infrared brightness of the clumps using Herschel and Spitzer data. Within the 6 newly observed hubs, we identify 67 cores, and find that the MMCs have masses between 15–911 M⊙ within a radius of 0.018–0.156 pc. The MMC of each hub contains 3–24 per cent of the clump mass (fMMC), becoming 5–36 per cent once core masses are normalised to the median core radius. Across the 35 clumps, we find no significant difference in the median fMMC values of hub and non-hub systems, likely the consequence of a sample bias. However, we find that fMMC is ∼7.9 times larger for infrared-dark clumps compared to infrared-bright ones. This factor increases up to ∼14.5 when comparing our sample of 6 infrared-dark hubs to infrared-bright clumps. We speculate that hub-filament systems efficiently concentrate mass within their MMC early on during its evolution. As clumps evolve, they grow in mass, but such growth does not lead to the formation of more massive MMCs.

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An ALMA View of Molecular Filaments in the Large Magellanic Cloud. II. An Early Stage of High-mass Star Formation Embedded at Colliding Clouds in N159W-South

Cited by 66 publications

References 78 publications

Classification of Filament Formation Mechanisms in Magnetized Molecular Clouds

Classification of Filament Formation Mechanisms in Magnetized Molecular Clouds

Radiation hydrodynamics simulations of massive star cluster formation in giant molecular clouds

An ALMA study of hub-filament systems – I. On the clump mass concentration within the most massive cores

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