José Manuel NievesSEGUIR Updated: Save Send news by mail electrónicoTu name *
Your email *
the formation of The Sun, of the Solar System and the subsequent emergence of life on Earth may have been one of the consequences of the impact of our galaxy, the Milky Way, with another, smaller, Sagittarius, discovered in 1990 and which now form part of the group of dwarf galaxies that orbit our own.
astronomers already knew that Sagittarius had struck on several occasions against the disk of stars of the Milky Way , and in previous studies already suggested that this had had a profound effect on the way in which the stars move within our galaxy. Some even went on to state that the spiral shape of the Milky Way galaxy, 10,000 times more massive than Sagittarius, is due in good part to the three impacts that we know that happened during the last 6,000 million years.
Now, a new study based on data of the european mission Gaia, which aims to build a three-dimensional map of the Milky Way with the movements and detailed positions of a billion stars, has revealed for the first time that l to influence of Sagittarius could have been of vital importance to , also, for our own existence.
In fact, the waves generated by the repeated collisions appear to have been responsible for triggering the main episodes of star formation in the history of our galaxy . And one of these episodes coincides almost perfectly with the time of the formation of the Sun, about to 4,700 million years ago. The results of this research, done by Spanish scientists, was just published in “Nature ” Astronomy”.
“we Know from existing models that Sagittarius collided with the Milky Way three times -explained Tomás Ruiz-Lara , of the Institute of Astrophysics of the Canary islands and first author of the study-. The first is about 6,000 million years, the following approximately 2,000 million years ago, and the last makes about 1,000 million years ago. And when we look at the data of Gaia on the Milky Way we find that the three periods of increased star formation reached its maximum point causes 5,700 million years, 1,900 million years and 1,000 million years ago, which coincides with the moments in which it is believed that Sagittarius passed through the disk of the Milky Way”.
A galaxy quiet, until it reaches Sagittarius
To reach these conclusions, researchers looked at the stars contained in a sphere of space of 6,500 light-years radius around the Sun, and compared after the brightness, the distances and the colors of those stars with the data of the models of stellar evolution existing. According to Ruiz-Lara “has the sense” to think that the repeated encounters with Sagittarius would have the effect of promoting the formation of waves of new stars in our Milky Way.
“at The beginning -explains the researcher – we have a galaxy, the Milky Way, are relatively quiet. After a violent period of initial star formation, in part triggered by an anterior fusion, which we describe in a another study, the Milky Way had reached a state of equilibrium in which the stars were formed in a constant manner. Suddenly, you have a Sagittarius to fall and disrupting that balance, doing that all of the gas and the dust previously immobile within the galaxy’s largest to be agitated like the waves on the water “.
In some areas of the Milky Way, these waves led to a greater concentration of dust and gas, while others remained relatively empty. Then, the high density of materials in these areas prompted the birth of new stars.
is The source of many of the stars that we see?
“it Seems that Sagittarius is not only modeled the shape of the Milky Way and influenced the way in which the stars move in their interior -he affirms for his part, Carme Gallart , who also wrote the research – but also helped the construction of our galaxy. It seems that an important part of the stellar mass of the Milky Way was formed due to the interactions with Sagittarius. Otherwise those stars would not exist”.
In fact, it seems quite possible that even the Sun and its planets would not have come to be existing if Sagittarius, trapped by the gravity of our galaxy, would not have collided with her, crossing his disc.
“The Sun continues, Gallart – was born at the same time that other stars are also formed in the galaxy because of the first encounter with Sagittarius. We do not know if a particular cloud of gas and dust that ended up giving him the distinction in the Sun collapsed or not because of the effects caused by Sagittarius . But it is a possible scenario because the age of the Sun is consistent with that of a star formed as a result of the effect of Sagittarius”.
Each new collision stripped Archer of some of its gases and dust, leaving the galaxy smaller after each step. And what is more, the existing data suggest that Sagittarius may have passed again through the disk of the Milky Way in the past hundreds of millions of years, as it is currently very close to him. The new study found evidence of a recent burst of star formation, suggesting a possible new wave of star birth in progress.
According to Timo Prusti , principal investigator of the project Gaia of the European Space Agency, such details about the history of the Milky Way would not be possible without Gaia , released at the end of 2013, whose two sets of data, released in 2016 and 2018, have revolutionized the study of our galaxy.
“Before they had determined some aspects of the history of star formation in the Milky Way -explains Prusti – based on data of the mission Hipparcos in the early 1990s. But those comments focused on the immediate vicinity of the Sun. It was not something truly representative and, therefore, could not discover those explosions of star formation that we see now.
This is really the first time we can see a detailed history of star formation in the Milky Way. It is a testimony to the scientific power of Gaia, which we have seen manifest itself time and time again in countless studies innovative in a period of only a couple of years.”