A large group of stars with unusual motion paths point to the collision of the Milky Way with another galaxy, which occurred more than eight billion years ago.
The modern form and appearance of our Galaxy is largely determined by the disaster that occurred with it before the formation of the Sun - between 8 and 10 billion years ago. During this period the Milky Way collided with dwarf galaxies and swallowed them, and itself experienced a serious structural rearrangement. To such conclusions, the scientists came, analyzing the observational data of the Gaia space telescope.
It seems that the missing star cluster has a rectangular shape, so it is called "Gaia Sosis". He himself did not survive the crash, and only the remains scattered along the Milky Way showed him. About this Vasily Belokurov from Cambridge and his colleagues wrote in an article in the journal Monthly Notices of the Royal Astronomical Society. This publication is accompanied by a series of materials at the open electronic library arXiv.org, which discloses various details of this work.
ESA Gaia's space observatory is the most precise astrometric observation by measuring the position and speed of the stars of the Milky Way. The authors rely on data within 10 parsecs of the Sun, as well as data on Sloan viewing the sky (SDSS). They examined the relationship between the contents of the star element heavier than helium (metal) and its movements. During the operation, the scientists saw a group of stars evolving relatively high metallicity and large radial velocities.Unlike most stars in the galaxy, they do not move at a constant around distance from the center, merge with it or move away from it. In addition, the star of the group that forms a rectangular area - "Gaia sausageВ».
The Milky Way's merger and collision will go through its entire life, but the encounter with "Gaia sausage» is one of the most dramatic, its mass is more than 10 billion solar masses (about ten times easier for the Milky Way), and from there in our galaxy at least eight cluster of stars, indicating the size of the subject of a deceased is very feasible.Computer simulations show the collision as a "sausage" the star is in an eccentric orbit around the center of the Milky Way and gradually absorbed by his disc.
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