The Magellanic Stream is the most massive and extended gaseous structure in the Milky Way halo, spanning the southern Galactic sky, with the potential to provide \(>10^{9}\,M_\odot\) of gaseous fuel for future star formation in our home Galaxy. It formed through tidal and hydrodynamical interactions between the Milky Way and its two dwarf satellites, the LMC and SMC. Because the Magellanic Stream is a remnant of these interactions, its observed properties provide the most direct observational signature for disentangling the Clouds’ complex orbital history.
From the Plane Quasar Survey, which probes halo gas at low Galactic latitudes, we discovered that the Magellanic Stream extends to the northern side of the Galactic plane!
We detected only C IV, along with Si IV in some sight lines, and no low ions, indicating that this gas is highly ionized with an estimated temperature of \(T \sim 10^{5.3}\) K (Choi et al., 2025). Based on its kinematic alignment and ionization trend consistent with the Magellanic Stream, we suggest that these absorbers are associated with it. The existence of highly ionized gas at a location above the Galactic plane may constrain the orbital direction of the Magellanic Clouds.
