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 |