Milky Way
Credit: CC0 Public Domain

A team led by researchers at Lund University in Sweden used data from the Gaia space telescope to show that parts of the disk vibrate. The ripples are caused by a dwarf galaxy that shook our universe hundreds of millions of years ago.

Between 100 and 400 billion stars make up the universe. The universe was formed from a cloud of gas consisting of hydrogen and helium. The gas was collected in a rotating disk and the stars were formed.

The research team presented their findings about the stars in the outer regions in a new study.

The stars are moving at different speeds. When the dwarf galaxy Sagittarius passed the Milky Way, it created wave motions similar to when a stone is dropped into a pond.

The research team was able to study a larger area of the disk thanks to the data from the European space telescope. Researchers have begun to piece together a complex puzzle by measuring the ripples in different parts of the disk.

"At the moment, Sagittarius is being torn apart, but more than a billion years ago it was much larger, probably 20% of the mass of the Milky Way's disk," said Paul McMillan.

The researchers were surprised by the amount of data they were able to use. The movement across the sky of two billion stars and the movement towards or away from us has been measured by the telescope since it was first used.

In the same way that geologists draw conclusions about the structure of the Earth from the seismic waves that travel through it, we can study the Milky Way using this new discovery. This type of seismology will teach us a lot about our home universe.

More information: Paul J McMillan et al, The disturbed outer Milky Way disc, Monthly Notices of the Royal Astronomical Society (2022). DOI: 10.1093/mnras/stac2571 Journal information: Monthly Notices of the Royal Astronomical Society