The Plane Quasar Survey: An Ionized Extension of the Magellanic Stream on the Northern Side of the Galactic Plane
Bo-Eun Choi, Jessica K. Werk, Kirill Tchernyshyov, Mary E. Putman, Yong Zheng, J. E. G. Peek, Hannah Bish, David Schiminovich

TL;DR
This paper reports the discovery of an extended ionized component of the Magellanic Stream on the northern side of the Galactic plane, revealing new insights into its structure, ionization state, and kinematics.
Contribution
It presents the first detection of ionized gas extension of the Magellanic Stream beyond previous limits using HST/COS spectra, indicating a larger mass and recent stripping history.
Findings
Detected C IV absorbers 60° beyond known ionized extent
Indicates highly ionized gas with T ~ 10^5.3 K
Suggests recent gas stripping and constraints on Magellanic Clouds' orbit
Abstract
The Magellanic Stream (MS) is a vast gaseous structure in the Milky Way halo, containing most of its mass in ionized form and tracing the interaction between the Large and Small Magellanic Clouds and the Galaxy. Using HST/COS G160M spectra from the Plane Quasar Survey, we detect C IV absorbers likely associated with the MS, extending to the northern side of the Galactic plane, approximately 60 beyond its previously known ionized extent. These absorbers exhibit position and kinematic alignment and show consistent ionization trends with previously studied MS sight lines. The non-detection of low ions such as Al II and Si II, and the detection of C IV (and Si IV in some sightlines), indicates a highly ionized gas phase. The observed Si IV/C IV column density ratios suggest a gas temperature of ~K and favor collisional ionization over photoionization. We estimate…
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Taxonomy
TopicsAstrophysics and Star Formation Studies · Astronomy and Astrophysical Research · Stellar, planetary, and galactic studies
