The interactions between the Milky Way and the galaxy of Sagittarius are known and have been the subject of previous work: the dwarf has proved to be a ‘difficult’ neighbor over time, given that it has repeatedly impacted on the disk of our galaxy because of gravitational forces. These interactions also had a profound effect on movement of the stars in Milky Way and some scholars even claim that its spiral structure may be due to at least three collisionsoccurred in the past 6 billion years. According to new research, the ripples produced by the bumps would seem to have unleashed star formation processes particularly intense, one of which can be dated to 4.7 billion years ago or the era in which the Solar system. Analyzing the data of Gaiain fact, astronomers have identified three periods where a peak in the birth of new stars (the first 5.7 billion years ago, the second 1.9 and the third 1), corresponding to the occasions when the galaxy of the Sagittarius it should be past through the disc of the Milky Way.
So, the dwarf galaxy would ‘liven up’ the state of Milky Way, which after an intense initial phase of star formation, had reached its own stability. In addition, the galaxy of Sagittarius – which is reduced after each clash – would be at the origin of a accretion of its neighbor: a conspicuous part of the stellar mass of the Milky Way it would have formed just for the interactions with the dwarf. The Sun and its planets perhaps would not have existed if the galaxy of the Sagittarius had not been attracted to gravitational force of ours, an event that would have ‘given way’ to interactions mentioned above.
Finally, the Nature Astronomy study has identified a new ‘bloom’ of baby stars which suggests a passage of the dwarf through the disk of the Milky Way in times rather recent astronomically (a few hundred million years). A look so detailed in the folds of the our galaxy – according to the researchers – it would not have been possible without the extraordinary contribution of Gaia, in which the our country is involved significantly, through theAsi and theInaf participating in the DPAC (Data Processing and TOnalysis Consortium).
Above: the interactions between the Milky Way and the Sagittarius galaxy (Credits: ESA)