快猫短视频

A collision 8 to 10 billion years ago between our own Milky Way and a smaller galaxy dubbed 鈥渢he sausage鈥� helped grow stars in the centre of the Milky Way, including our own sun. The smaller galaxy was torn apart in the collision, providing extra gases to fuel star formation.

The crash would have lasted many hundreds of millions of years. Stars from the smaller galaxy have ended up with strange, sausage-shaped orbits around the centre of the Milky Way 鈥� hence the name.

Wyn Evans at the University of Cambridge and his colleagues 聽by analysing data gathered by the European Space Agency鈥檚 Gaia spacecraft and ground-based telescopes.

Fast stars

The team聽looked at the current velocities and chemical composition of stars in the Milky Way. They found that the stars in sausage-shaped orbits are now travelling at around 400 kilometres per second, twice the velocity of our own sun and the other native stars, and abruptly reverse each time they reach the end of their sausage orbit.

The collision also brought in huge supplies of new gas which helped more stars in the Milky Way form and mature, including our own sun. 鈥淕alaxies are essentially machines for converting gas into stars,鈥� says Evans.

He says that there would already have been a disc of stars in the centre of the Milky Way, and the extra gases and material from the dismembered sausage galaxy would have helped accelerate star formation.

Data from Gaia on the velocities also helped the team identify the position of each star from the sausage, meaning they could use Earth-based telescopes to examine their chemical makeup. These showed the sausage-derived stars had different chemical compositions and less metallic content compared to native stars.