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The Magellanic Stream: Implications of the Magellanic Corona and new Orbital Histories of the Clouds

Presentation #403.05 in the session “Galactic Streams and Structures”.

Published onJun 01, 2021
The Magellanic Stream: Implications of the Magellanic Corona and new Orbital Histories of the Clouds

The Magellanic Stream is a massive gaseous structure associated with the Milky Way’s two most massive dwarf satellites: the Large and Small Magellanic Clouds. While the 400 million solar masses of neutral HI gas was first mapped in 1974, recent spectroscopic absorption line studies have shown that there are ~2 billion solar masses of ionized gas associated with the Magellanic Stream. Until now, there hasn’t been an explanation for this massive amount of ionized gas in tidal models. Here we present novel models of the formation and evolution of the Magellanic System through mutual tidal interactions between the Large and Small Magellanic Clouds over the course of the past several billion years. For the first time, we also include a Magellanic Corona of warm, ionized gas around the Magellanic Clouds in addition to a hot gaseous halo around the Milky Way. This Magellanic Corona is well motivated by the high mass of the LMC (>1011 solar masses), the discovery of other dwarf galaxies that likely fell in towards the Milky Way with the Magellanic Clouds (members of a Magellanic Group), as well as the warm circumgalactic gas surrounding LMC-like galaxies in cosmological simulations. As the Magellanic Clouds interact throughout their history, the neutral gas is stripped from their disks to form the HI Stream, while the Magellanic Corona is stretched and warped by the gravitational field of the Milky Way to cocoon the Stream in ionized gas. This new model can account for both the mass of the neutral Stream as well as the total mass of the ionized gas component. Additionally, we will show preliminary results in which we have explored alternate orbital histories of the Clouds on their approach to the Milky Way. These new orbits could have a dramatic effect on our understanding of the Stream and its 3D position around our Galaxy.

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