Building Andromeda: Galaxy ended up with stars orbiting at right angles

[smp]

From Ars Technica:

"The large galaxies present in the current Universe weren't always so big. Evidence indicates that they were built up over time, largely by collisions with other galaxies. These collisions have left marks that we can still detect: streams of stars that were drawn in from the victims of the collisions, and faint dwarf galaxies that still orbit the larger object that devoured many of their stars. With enough data, it's possible to become a galactic historian and reconstruct the events that brought the modern-day giants to their present form."

https://arstechnica.com/science/2019/10 ... ht-angles/

smp