The VMC survey -- XLVII. Turbulence-Controlled Hierarchical Star Formation in the Large Magellanic Cloud

Abstract

We perform a statistical clustering analysis of upper main-sequence stars in the Large Magellanic Cloud (LMC) using data from the Visible and Infrared Survey Telescope for Astronomy survey of the Magellanic Clouds. We map over 2500 young stellar structures at 15 significance levels across ∼120 square degrees centred on the LMC. The structures have sizes ranging from a few parsecs to over 1 kpc. We find that the young structures follow power-law size and mass distributions. From the perimeterarea relation, we derive a perimeter-area dimension of 1.44±0.20. From the mass-size relation and the size distribution, we derive two-dimensional fractal dimensions of 1.50±0.10 and 1.61±0.20, respectively. We find that the surface density distribution is well-represented by a lognormal distribution. We apply the Larson relation to estimate the velocity dispersions and crossing times of these structures. Our results indicate that the fractal nature of the young stellar structures has been inherited from the gas clouds from which they form and that this architecture is generated by supersonic turbulence. Our results also suggest that star formation in the LMC is scale-free from 10 pc to 700 pc.

Topography of the Young Galactic Disk: Spatial and Kinematic Patterns of the Clustered Star Formation in the Solar Neighborhood

“…At smaller scales where our analysis is relevant, turbulence is probably the main mechanism controlling the underlying structure where coherent star formation occurs. Our result is consistent with a recent detailed analysis of the distribution of ∼ 2500 young stellar structures in the Large Magellanic Cloud by Miller et al (2022), who derived a twodimensional fractal dimension of around 1.5 − 1.6 in the range of spatial scales from 10 pc to 700 pc. The value D c = 1.62 ± 0.05 implies that the corresponding threedimensional fractal dimension should be D f = 2.5 − 2.6 (see Table 1 in Sánchez & Alfaro 2008), which is similar to the range of values D f ∼ 2.5 − 2.7 obtained from emission maps of several spectral lines for different molecular clouds in the Milky Way (Sánchez et al 2005(Sánchez et al , 2007b) and for early-type stars in the GB (Sánchez et al 2007a).…”