The VMC Survey. XXVII. Young Stellar Structures in the LMC's Bar Star-forming Complex

Ning Chen Sun, Richard De Grijs, Smitha Subramanian, Kenji Bekki, Cameron P.M. Bell, Maria Rosa L. Cioni, Valentin D. Ivanov, Marcella Marconi, Joana M. Oliveira, Andrés E. Piatti, Vincenzo Ripepi, Stefano Rubele, Ben L. Tatton, Jacco Th Van Loon

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Abstract

Star formation is a hierarchical process, forming young stellar structures of star clusters, associations, and complexes over a wide range of scales. The star-forming complex in the bar region of the Large Magellanic Cloud is investigated with upper main-sequence stars observed by the VISTA Survey of the Magellanic Clouds. The upper main-sequence stars exhibit highly nonuniform distributions. Young stellar structures inside the complex are identified from the stellar density map as density enhancements of different significance levels. We find that these structures are hierarchically organized such that larger, lower-density structures contain one or several smaller, higher-density ones. They follow power-law size and mass distributions, as well as a lognormal surface density distribution. All these results support a scenario of hierarchical star formation regulated by turbulence. The temporal evolution of young stellar structures is explored by using subsamples of upper main-sequence stars with different magnitude and age ranges. While the youngest subsample, with a median age of log(τ/yr) = 7.2, contains the most substructure, progressively older ones are less and less substructured. The oldest subsample, with a median age of log(τ/yr) = 8.0, is almost indistinguishable from a uniform distribution on spatial scales of 30-300 pc, suggesting that the young stellar structures are completely dispersed on a timescale of ∼100 Myr. These results are consistent with the characteristics of the 30 Doradus complex and the entire Large Magellanic Cloud, suggesting no significant environmental effects. We further point out that the fractal dimension may be method dependent for stellar samples with significant age spreads.

LanguageEnglish
Article number149
JournalAstrophysical Journal
Volume849
Issue number2
DOIs
StatePublished - 10 Nov 2017

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stellar structure
main sequence stars
Magellanic clouds
stars
star formation
star clusters
substructures
mass distribution
density distribution
fractals
temporal evolution
environmental effect
turbulence
power law
young
augmentation
timescale
distribution

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Sun, N. C., Grijs, R. D., Subramanian, S., Bekki, K., Bell, C. P. M., Cioni, M. R. L., ... Loon, J. T. V. (2017). The VMC Survey. XXVII. Young Stellar Structures in the LMC's Bar Star-forming Complex. Astrophysical Journal, 849(2), [149]. DOI: 10.3847/1538-4357/aa911e
Sun, Ning Chen ; Grijs, Richard De ; Subramanian, Smitha ; Bekki, Kenji ; Bell, Cameron P.M. ; Cioni, Maria Rosa L. ; Ivanov, Valentin D. ; Marconi, Marcella ; Oliveira, Joana M. ; Piatti, Andrés E. ; Ripepi, Vincenzo ; Rubele, Stefano ; Tatton, Ben L. ; Loon, Jacco Th Van. / The VMC Survey. XXVII. Young Stellar Structures in the LMC's Bar Star-forming Complex. In: Astrophysical Journal. 2017 ; Vol. 849, No. 2.
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Sun, NC, Grijs, RD, Subramanian, S, Bekki, K, Bell, CPM, Cioni, MRL, Ivanov, VD, Marconi, M, Oliveira, JM, Piatti, AE, Ripepi, V, Rubele, S, Tatton, BL & Loon, JTV 2017, 'The VMC Survey. XXVII. Young Stellar Structures in the LMC's Bar Star-forming Complex' Astrophysical Journal, vol 849, no. 2, 149. DOI: 10.3847/1538-4357/aa911e

The VMC Survey. XXVII. Young Stellar Structures in the LMC's Bar Star-forming Complex. / Sun, Ning Chen; Grijs, Richard De; Subramanian, Smitha; Bekki, Kenji; Bell, Cameron P.M.; Cioni, Maria Rosa L.; Ivanov, Valentin D.; Marconi, Marcella; Oliveira, Joana M.; Piatti, Andrés E.; Ripepi, Vincenzo; Rubele, Stefano; Tatton, Ben L.; Loon, Jacco Th Van.

In: Astrophysical Journal, Vol. 849, No. 2, 149, 10.11.2017.

Research output: Contribution to journalArticle

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T1 - The VMC Survey. XXVII. Young Stellar Structures in the LMC's Bar Star-forming Complex

AU - Sun,Ning Chen

AU - Grijs,Richard De

AU - Subramanian,Smitha

AU - Bekki,Kenji

AU - Bell,Cameron P.M.

AU - Cioni,Maria Rosa L.

AU - Ivanov,Valentin D.

AU - Marconi,Marcella

AU - Oliveira,Joana M.

AU - Piatti,Andrés E.

AU - Ripepi,Vincenzo

AU - Rubele,Stefano

AU - Tatton,Ben L.

AU - Loon,Jacco Th Van

PY - 2017/11/10

Y1 - 2017/11/10

N2 - Star formation is a hierarchical process, forming young stellar structures of star clusters, associations, and complexes over a wide range of scales. The star-forming complex in the bar region of the Large Magellanic Cloud is investigated with upper main-sequence stars observed by the VISTA Survey of the Magellanic Clouds. The upper main-sequence stars exhibit highly nonuniform distributions. Young stellar structures inside the complex are identified from the stellar density map as density enhancements of different significance levels. We find that these structures are hierarchically organized such that larger, lower-density structures contain one or several smaller, higher-density ones. They follow power-law size and mass distributions, as well as a lognormal surface density distribution. All these results support a scenario of hierarchical star formation regulated by turbulence. The temporal evolution of young stellar structures is explored by using subsamples of upper main-sequence stars with different magnitude and age ranges. While the youngest subsample, with a median age of log(τ/yr) = 7.2, contains the most substructure, progressively older ones are less and less substructured. The oldest subsample, with a median age of log(τ/yr) = 8.0, is almost indistinguishable from a uniform distribution on spatial scales of 30-300 pc, suggesting that the young stellar structures are completely dispersed on a timescale of ∼100 Myr. These results are consistent with the characteristics of the 30 Doradus complex and the entire Large Magellanic Cloud, suggesting no significant environmental effects. We further point out that the fractal dimension may be method dependent for stellar samples with significant age spreads.

AB - Star formation is a hierarchical process, forming young stellar structures of star clusters, associations, and complexes over a wide range of scales. The star-forming complex in the bar region of the Large Magellanic Cloud is investigated with upper main-sequence stars observed by the VISTA Survey of the Magellanic Clouds. The upper main-sequence stars exhibit highly nonuniform distributions. Young stellar structures inside the complex are identified from the stellar density map as density enhancements of different significance levels. We find that these structures are hierarchically organized such that larger, lower-density structures contain one or several smaller, higher-density ones. They follow power-law size and mass distributions, as well as a lognormal surface density distribution. All these results support a scenario of hierarchical star formation regulated by turbulence. The temporal evolution of young stellar structures is explored by using subsamples of upper main-sequence stars with different magnitude and age ranges. While the youngest subsample, with a median age of log(τ/yr) = 7.2, contains the most substructure, progressively older ones are less and less substructured. The oldest subsample, with a median age of log(τ/yr) = 8.0, is almost indistinguishable from a uniform distribution on spatial scales of 30-300 pc, suggesting that the young stellar structures are completely dispersed on a timescale of ∼100 Myr. These results are consistent with the characteristics of the 30 Doradus complex and the entire Large Magellanic Cloud, suggesting no significant environmental effects. We further point out that the fractal dimension may be method dependent for stellar samples with significant age spreads.

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Sun NC, Grijs RD, Subramanian S, Bekki K, Bell CPM, Cioni MRL et al. The VMC Survey. XXVII. Young Stellar Structures in the LMC's Bar Star-forming Complex. Astrophysical Journal. 2017 Nov 10;849(2). 149. Available from, DOI: 10.3847/1538-4357/aa911e