A team using Gaia data to study the structure of our Milky Way galaxy has published a new paper in the journal Nature Astronomy, describing the warp of our galaxy and attributing it to a collision. Now, in general, galactic warps are thought to pretty much always come from a collision, so by itself this isn’t all that newsworthy. This team actually buried the lede, however, and in the third section of the release they contend that the Sagittarius dwarf galaxy might just be driving this warp with its ongoing merger into the Milky Way. Gaia’s amazingly precise measurements of stellar positions and motions have allowed them to not just trace out the shape of the Milky Way’s warp, but to also measure how it is moving. They have determined that the warp itself will appear to make one full precession about the galaxy every 600-700 million years, as it’s constitution stars move around our galaxy in bobbing orbits. The warp itself moves slower than the stars, which can complete a cycle in 200-300 million years. This story takes a known concept – collisions make warps – and paints in amazing details, showing once again that science is an incremental process.

Read ESA’s story at:

Milky Way’s warp caused by galactic collision, Gaia suggests (ESA)