Scientists from the University of Michigan came to the conclusion that the Andromeda galaxy 2 billion years ago crushed and destroyed a massive galaxy. Despite oblivion, the galaxy left a rich trace: an almost invisible halo of stars (larger than the Andromeda galaxy), an elusive stellar stream and a separate mysterious compact galaxy M32.
Destroyed galaxy called M32p. She was the third largest member of the Local Group of Galaxies, after the Milky Way and Andromeda. With the help of computer models, researchers were able to find evidence of a missing galaxy. Scientists have long known that this almost invisible large star halo contains the remnants of smaller eaten galaxies. It is believed that Andromeda managed to devour hundreds of its tinier brethren. It seemed to interfere with the study of the galaxy.
However, a new computer simulation was not embarrassed by the fact of absorption in the past and found that most of the stars of the external faint halo Andromeda contributed to the crushing of a large galaxy. That is, these data can be used to deduce the characteristics of the largest of the crushed galaxies. Galaxy M32 was 20 times larger than any galaxy merged with the Milky Way. It also stood out massively and became the third largest in the Local Group. This study indicates that the compact and dense galaxy M32 is the surviving center of the lost sister of the Milky Way. This is really a strange object, as it consists of many young stars and is considered the most compact galaxy among those known in the Universe!
These data may affect the traditional understanding of the process of galactic development. It turns out that the Andromeda disk survived after a strike with a massive galaxy. But then it makes one doubt that large collisions destroy disks and form an elliptical type. The timing of the merger may explain the thickening of the Andromeda disk, as well as the outbreak of stellar birth 2 billion years ago.
The researchers believe that the method used in their work can be applied to other galaxies, allowing you to measure the most massive galactic fusions. This will allow to understand the causes of the growth of galaxies and to track the impact of collisions.