A team of researchers from the Institute of Space Sciences of the University of Barcelona, Spain, and the University of Groningen, The Netherlands, have discovered, after analyzing data collected by the Gaia space mission, substructures in the Milky Way that have never been detected before.
“We have seen substructures that have different shapes, such as the shape of a snail. The existence of such substructures in the Galaxy was observed for the first time, thanks to the unprecedented accuracy of data collected by the Gaia satellite of the European Space Agency, - said Teresa Antoja of the Institute of Space Sciences, who is the main author of the new scientific work. "These substructures allow us to conclude that the disk of our Galaxy experienced powerful gravitational disturbances about 300 and 900 million years ago, respectively."
But what could have caused these indignations? To answer this question, the researchers compared the structure and depth of distortion of the spiral structure with models of the dynamics of the Galaxy. This made it possible to develop a hypothesis according to which such a gravitational "shake" was caused by the passage of the Sagittarius dwarf galaxy past the Milky Way.
“Our research suggests that the disk of our Galaxy is dynamically young, sensitive to disturbances and changing over time,” Antoya says. "One of the most notable structures we've seen is the spiral structure that includes stars close to the Sun - never seen before by anyone."
Like a stone thrown into a pond, or a magnet approaching a sheet of paper with iron filings lying on it, a dwarf galaxy passing by a larger galaxy causes disturbances in the structure of this larger galaxy, the authors of the work illustrated their hypothesis. Subsequently, the Sagittarius dwarf galaxy - like dozens of other small galaxies - was absorbed by our Galaxy and became part of it, the researchers added.
The work was published in the journal Nature.
