An ancient remnant of a galactic collision encircles the Sombrero Galaxy

Astronomers have found a huge ring structure looping around the nearby (and absolutely spectacular) galaxy M104, also known as the Sombrero Galaxy. It’s likely elliptical, encircling the entire galaxy and something like 370,000 light years along its long axis.

This ring is almost certainly made up of stars, and is what’s called a stellar stream, the remnants of a smaller galaxy eaten by a bigger one. It’s known that the Sombrero suffered a massive collision more than 3.5 billion years ago, but ...