Milky Way

In addition to the stellar halo, our galaxy is also surrounded by a halo made of hot gas, which is much more extensive than the stellar halo.

An excerpt from the article 16 facts about Milky Way

Its temperature is from 1 million to 2.5 million degrees Celsius and it extends for hundreds of thousands of light-years from the galactic center to the neighboring satellite galaxies - the Small Magellanic Cloud and the Large Magellanic Cloud, and its mass is almost equal to the mass of the Milky Way itself.