ERRATUM: “THE FRACTAL DIMENSION OF STAR-FORMING REGIONS AT DIFFERENT SPATIAL SCALES IN M33” (2010, ApJ, 720, 541)

Sánchez, Néstor; Añez, Neyda; Alfaro, E. J.; Odekon, Mary Crone

doi:10.1088/0004-637x/723/1/969

Cited by 18 publications

(20 citation statements)

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“…The similarity between the cluster mass-function and the stellar mass-function seems to originates from the self-similar structure of GMC, as was also discussed in Elmegreen (2002). From an observational perspective, the relation between the self-similar structure of GMCs and star forming regions has been suggested by (Elmegreen & Falgarone 1996;Elmegreen & Scalo 2004;Sánchez et al 2010). As can be seen in Figure 7, more massive clusters tend to form in densiter regions.…”

Section: The Self-similarity Between the Stellar Mass Function And Th...mentioning

confidence: 73%

The initial mass function of star clusters that form in turbulent molecular clouds

Fujii

Zwart

2015

Monthly Notices of the Royal Astronomical Society

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We simulate the formation and evolution of young star clusters using the combination of smoothed-particle hydrodynamical (SPH) simulations and direct N -body simulations. We start by performing SPH simulations of the giant molecular cloud with a turbulent velocity field, a mass of 4 × 10 4 to 5 × 10 6 M ⊙ , and a density between ρ ∼ 1.7×10 3 and 170cm −3 . We continue the hydrodynamical simulations for a free-fall time scale (t ff ≃ 0.83 Myr and 2.5 Myr), and analyze the resulting structure of the collapsed cloud. We subsequently replace a density-selected subset of SPH particles with stars by adopting a local star-formation efficiency proportional to ρ 1/2 . As a consequence, the local star formation efficiency exceeds 30 per cent, whereas globally only a few per cent of the gas is converted to stars. The stellar distribution by the time gas is converted to stars is very clumpy, with typically a dozen bound conglomerates that consist of 100 to 10 4 stars. We continue to evolve the stars dynamically using the collisional N -body method, which accurately treats all pairwise interactions, stellar collisions and stellar evolution. We analyze the results of the N -body simulations when the stars have an age of 2 Myr and 10 Myr. During the dynamical simulations, massive clusters grow via hierarchical merging of smaller clusters. The shape of the cluster mass function that originates from an individual molecular cloud is consistent with a Schechter function with a power-law slope of β = −1.73 at 2 Myr and β = −1.67 at 10 Myr, which fits to observed cluster mass function of the Carina region. The superposition of mass functions have a power-law slope of < ∼ − 2, which fits the observed mass function of star clusters in the Milky Way, M31 and M83. We further find that the mass of the most massive cluster formed in a single molecular cloud with a mass of M g scales with 6.1M 0.51 g which also agrees with recent observation of the GMC and young clusters in M51.

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Section: The Self-similarity Between the Stellar Mass Function And Th...mentioning

confidence: 73%

The initial mass function of star clusters that form in turbulent molecular clouds

Fujii

Zwart

2015

Monthly Notices of the Royal Astronomical Society

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“…Several studies also explored the maximum size of the star-forming region over which star formation is physically correlated (Grasha et al 2017). Sánchez et al (2010); Grasha et al (2017); Jimena Rodríguez et al (2020) used the detected stars and clusters in selected nearby galaxies and reported a length scale between 200 to 1000 pc for such largest hierarchical structures. In this study, we used the FUV flux map to identify individual clumps or large structures in the observed image.…”

Section: Identification Of Young Star-forming Clumpsmentioning

confidence: 99%

Tracing young star-forming clumps in the nearby flocculent spiral galaxy NGC 7793 with UVIT imaging

Mondal,

Subramaniam,

George

et al. 2021

Preprint

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Star formation in galaxies is a hierarchical process with a wide range of scales from smaller clusters to larger stellar complexes. Here, we present an ultra-violet imaging study of the nearby flocculent spiral galaxy NGC 7793, observed with the Ultra-Violet Imaging Telescope (UVIT). We find that the disk scale-length estimated in Far-UV (2.64±0.16 kpc) is larger than that in Near-UV (2.21±0.21 kpc) and optical (1.08 kpc), which supports the inside-out growth scenario of the galaxy disk. The star-forming UV disk is also found to be contained within the extent of H I gas of column density greater than 10 21 cm −2 . With the spatial resolution of UVIT (1 pixel ∼ 6.8 pc), we identified 2046 young star-forming clumps in the galaxy with radii between ∼ 12 -70 pc, which matches well with the size of GMCs detected in the galaxy. Around 61% of the regions identified in our study have age younger than 20 Myr, which points to a recent enhancement of star formation across the galaxy. We also noticed that the youngest star-forming regions, with age < 10 Myr, distinctly trace the flocculent arms of the galaxy. The estimated mass of the clumps cover a range between 10 3 − 10 6 M . We noticed a gradient in the mass distribution of identified clumps along the spiral arms. We have also studied the nuclear star cluster of the galaxy and found that the stellar populations in the cluster outskirts are younger than the inner part.

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“…(ii) even when density fluctuations dominate, there are distinct methods for estimating the fractal dimension, D, which lead to significantly different values of a = D − 2 (Federrath et al 2009;Federrath, private communication). Sánchez et al (2010) carried out a detailed fractal analysis of M 33, and showed that the distribution of molecular gas undergoes a transition from fractal to homogeneous at scales roughly comparable to the disc scale height. This suggests that a ≈ 0 for ℓ > ∼ h. Concerning the value of b, Kim et al (2007) analysed the physical properties of atomic gas in the Large Magellanic Cloud, and found that the linewidth-size scaling relation of H i clouds is a simple power law up to scales of a few kpc.…”

Section: Role Of the Disc Scale Heightmentioning

confidence: 99%

Larson's scaling laws, and the gravitational instability of clumpy discs at high redshift

Romeo

Agertz

2014

Monthly Notices of the Royal Astronomical Society

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Gravitational instabilities play a primary role in shaping the clumpy structure and powering the star formation activity of gas-rich high-redshift galaxies. Here we analyse the stability of such systems, focusing on the size and mass ranges of unstable regions in the disc. Our analysis takes into account the mass-size and linewidth-size scaling relations observed in molecular gas, originally discovered by Larson. We show that such relations can have a strong impact on the size and mass of star-forming clumps, as well as on the stability properties of the disc at all observable scales, making the classical Toomre parameter a highly unreliable indicator of gravitational instability. For instance, a disc with Q = 1 can be far from marginal instability, while a disc with Q ≪ 1 can be marginally unstable. Our work raises an important caveat: if clumpy discs at high redshift have scale-dependent surface densities and velocity dispersions, as implied by the observed clump scaling relations, then we cannot thoroughly understand their stability and star formation properties unless we perform multi-scale observations. This will soon be possible thanks to dedicated ALMA surveys, which will explore the physical properties of super-giant molecular clouds at the peak of cosmic star formation and beyond.

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ERRATUM: “THE FRACTAL DIMENSION OF STAR-FORMING REGIONS AT DIFFERENT SPATIAL SCALES IN M33” (2010, ApJ, 720, 541)

Cited by 18 publications

References 0 publications

The initial mass function of star clusters that form in turbulent molecular clouds

The initial mass function of star clusters that form in turbulent molecular clouds

Tracing young star-forming clumps in the nearby flocculent spiral galaxy NGC 7793 with UVIT imaging

Larson's scaling laws, and the gravitational instability of clumpy discs at high redshift

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