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9th of June 2016
Hydrogen clouds in the Magellanic Leading Arm
by Bi-Qing For (UWA/ICRAR)
For et al. (2016) present a high-resolution study of five high-velocity clouds (HVCs) in the region of the Magellanic Leading Arm (LA). The goal of the study is to probe the multiphase structures of the clouds in order to give an insight of their origin, evolution and distance. High-resolution data were obtained from the Australia Telescope Compact Array (ATCA). The authors identify resolved and unresolved clumps and find a gradient in thermal halo pressure, hydrogen density and HI column density of HVC as a function of Galactic latitude. This is possibly the first observational evidence of varying distance in the Leading Arm region, with the leading part of the Leading Arm (LA II and III) probably being closer to the Galactic disc than the trailing end (LA I). Top left: the integrated HI column density map in the region of the LA as studied by For et al. (2013). Five HVCs at different Galactic latitudes were selected. Top right: Cloud with unresolved multiphase structures. Double Gaussian profiles are fitted to the spectrum. Bottom: Examples of integrated HI column density maps of the combined Parkes and ATCA HI data set. The grey contours represent HI column densities in the Parkes Galactic All-Sky Survey (GASS; McClure-Griffiths et al. 2009) data set. Center of the cloud has been resolved to small clumps. The arrows point in the direction of the Galactic Plane.

References: B.-Q. For, L. Staveley-Smith, N. M. McClure-Griffiths, T. Westmeier, and K. Bekki, 2016, MNRAS accepted

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