The Milky Way may have recently collided with something massive

The history of our Milky Way Galaxy is filled with a number of collisions with other galaxies. These collisions left traces on us. The types of wrinkles that form as a result of the oscillation of stars, which researchers from several universities have sifted through with the help of data sent by the Gaia mission. Because these wrinkles continue to reverberate through different families of stars, affecting their motion GaiaGaia He specifically has the task of measuring.

Wrinkles are a sign of life's accidents in the Milky Way

However, in the Milky Way, the wrinkles dissipate over time. So, by comparing observations – which show quite obvious wrinkles – with cosmological simulations, researchers have determined that our last major collision with another galaxy did not actually occur between 8 and 11 billion years ago (this one occurred 11 billion years ago). year). Astronomy scientistsAstronomy scientists Summon Gaia CollisionEnceladusEnceladus) as they previously thought, but much earlier, less than three billion years ago.

Researchers' works published in Monthly Notices of the Royal Astronomical Society It suggests that all these stars with unusual orbits that astronomers know so well do not ultimately come from the Gaia-Enceladus collision. But from another more recent event, it is described as fusionfusion Radial Virgo. Collision with a dwarf galaxy.

The collision turned the Milky Way upside down over the past billion years

“The history of the Milky Way is constantly being rewritten, thanks in large part to new data from Gaia.”“, explains Thomas Donlon, one of the study's co-authors, in A Press release from the European Space Agency (European Space AgencyEuropean Space Agency). He added: “This result, that a large portion of the Milky Way Galaxy joined us only in the last billion years, represents a major change from what astronomers had thought until now. » Because it now seems likely that the radial merger of Virgo brought with it another little family Dwarf galaxiesDwarf galaxies and star clusters, all of which joined the Milky Way at about the same time. Future exploration will reveal which of these small objects previously thought to be associated with the Gaia-Enceladus collision are in fact associated with a more recent radial merger of Virgo.