A detailed GASKAP-H i view of shells and loops in the Magellanic Bridge
Year: 2026
Type: article
Abstract: ABSTRACT We present 8-pc-scale Galactic Australian Square Kilometre Array Pathfinder-H i observations of an H i shell (diameter $\sim$130 pc) associated with the H $\alpha$ shell DEM171 in the Magellanic Bridge. The Bridge’s diffuse, H i-dominated environment, with minimal galactic shearing and fewer overlapping star-forming regions, provides an ideal environment to study cold gas formation driven by stellar feedback. To investigate the H i multiphase structure and kinematics of the shell, we perform Gaussian decomposition of H i line profiles. We identify cold H i components with velocity dispersions $\sigma \lt 2.5\, \mathrm{km}\, \mathrm{s}^{-1}$ located within the shell. Complementary Herschel far-infrared 250 $\rm{\mu m}$ and H $\alpha$ maps show that while the central cavity is ionized, the shell walls contain cold H i, molecular gas, and dust, suggesting that stellar feedback has promoted cold gas formation or swept pre-existing cold gas into the shell walls. We also identify cold H i clumps outside the shell tracing a larger-scale structure, MB-Loop I. To investigate the large-scale context, we apply a Fourier transform method to H i emission-line profiles to map the lower limit of cold gas column densities across a section of the Bridge, revealing structures from large loops to smaller shells. The association between MB-Loop I and the H i shell suggests that cold H i gas may pre-exist before shell expansion. Finally, the shell exhibits asymmetric expansion, with a preferred orientation roughly perpendicular to the arc along MB-Loop I. Our results show that cold H i gas exists across a wide range of spatial scales in the Magellanic Bridge, highlighting the dynamic interplay that shapes the surrounding interstellar medium.
Authors: Shin-Jeong Kim, Antoine Marchal, N M McClure-Griffiths, J R Dawson, James Dempsey, Helga Dénes, John M Dickey, Steven J Gibson, Katie Jameson, Ian Kemp, Bumhyun Lee, Min-Young Lee, Adam K Leroy, Callum Lynn, Yik Ki Ma, Marc-Antoine Miville-Deschênes, Eric G M Muller, Claire Murray, Hiep Nguyen, Nickolas Pingel, Hye-Jin Park, Jacco Th van Loon
Institutions: Australian National University, Centre National de la Recherche Scientifique, Université Paris Cité, Université Paris Sciences et Lettres, Observatoire de Paris, École Normale Supérieure - PSL, Sorbonne Université, Laboratoire de Physique de l'Ecole Normale Supérieure, SKA Observatory, Australia Telescope National Facility, Macquarie University, Universidad San Francisco de Quito, University of Tasmania, Western Kentucky University, California Institute of Technology, Commonwealth Scientific and Industrial Research Organisation, Curtin University, International Centre for Radio Astronomy Research, Yonsei University, Korea Astronomy and Space Science Institute, The Ohio State University, Max Planck Institute for Radio Astronomy, Space Telescope Science Institute, University of Wisconsin–Madison, Indiana University Bloomington, Indiana University, Keele University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,046
OpenAlex ID: W7213563877