Structured star formation in the Magellanic inter-Cloud region

A. D. Mackey, S. E. Koposov, G. S. Da Costa, V. Belokurov, D. Erkal, F. Fraternali, N. M. McClure-Griffiths, M. Fraser

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We use a new contiguous imaging survey conducted using the Dark Energy Camera to investigate the distribution and properties of young stellar populations in the Magellanic inter-Cloud region. These young stars are strongly spatially clustered, forming a narrow chain of low-mass associations that trace the densest H I gas in the Magellanic Bridge and extend, in projection, from the SMC to the outer disc of the LMC. The associations in our survey footprint have ages ≲ 30 Myr, masses in the range ∼100-1200 M⊙ and very diffuse structures with half-light radii of up to ∼100 pc. The two most populous are strongly elliptical and aligned to ≈10°, with the axis joining the centres of the LMC and the SMC. These observations strongly suggest that the young inter-Cloud populations formed in situ, likely due to the compression of gas stripped during the most recent close LMC-SMC encounter. The associations lie at distances intermediate between the two Clouds, and we find no evidence for a substantial distance gradient across the imaged area. Finally, we identify a vast shell of young stars surrounding a central association, that is spatially coincident with a low column density bubble in the H I distribution. The properties of this structure are consistent with a scenario where stellar winds and supernova explosions from massive stars in the central cluster swept up the ambient gas into a shell, triggering a new burst of star formation. This is a prime location for studying stellar feedback in a relatively isolated environment.
Original languageEnglish
Pages (from-to)2975-2989
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - 1-Dec-2017


  • galaxies: interactions
  • galaxies: ISM
  • Magellanic Clouds
  • galaxies: star formation
  • galaxies: structure

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