Wisconsin: Massive Halo Finally Explains Magellanic Stream

[bystander]

Massive Halo Finally Explains Stream
of Gas Swirling around the Milky Way
University of Wisconsin, Madison | 2020 Sep 09

A view of the gas in the Magellanic System as it would appear in the night sky.The Magellanic Corona covers the entire sky while the Magellanic Stream is seen as gas flowing away from the two dwarf galaxies, the Large and the Small MagellanicClouds.This image is taken directly from the numerical simulations, however it has been modified slightly for aesthetics.(Credit: Colin Legg/Scott Lucchini)

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The Milky Way is not alone in its neighborhood. It has captured smaller galaxies in its orbit, and the two largest are known as the Small and Large Magellanic Clouds, visible as twin dusty smears in the Southern Hemisphere.

As the Magellanic Clouds began circling the Milky Way billions of years ago, an enormous stream of gas known as the Magellanic Stream was ripped from them. The stream now stretches across more than half of the night sky. But astronomers have been at a loss to explain how the stream became as massive at it is, over a billion times the mass of the sun.

Now, astronomers at the University of Wisconsin–Madison and their colleagues have discovered that a halo of warm gas surrounding the Magellanic Clouds likely acts as a protective cocoon, shielding the dwarf galaxies from the Milky Way’s own halo and contributing most of the Magellanic Stream’s mass. As the smaller galaxies entered the sphere of the Milky Way’s influence, parts of this halo were stretched and dispersed to form the Magellanic Stream. ...

The Magellanic Corona as the Key to the Formation of the Magellanic Stream ~ S. Lucchini et al

• Nature 585(7824):203 (10 Sep 2020) DOI: 10.1038/s41586-020-2663-4
• arXiv.org > astro-ph > arXiv:2009.04368 > 09 Sep 2020