The milky way is not moving in isolation through space, but has experienced in the course of its history of close approaches, or even violent collisions with neighboring galaxies. A part of these collisions, both partners came unscathed and exchanged only gas and stars with each other. In front of about ten billion years, the milky way has experienced such a violent collision with a dwarf galaxy that was completely torn. From the Remnants, and within our galaxy, around which are thrown the stars, the density of the “star bump” in the milky way centre and also a large part of the surrounding Halo probably originated. Observations of collisions of other galaxies also demonstrate that such events often lead to periods of increased star formation in the collision partners. The strong turbulence, promote the collapse of gas clouds and the formation of new stars.
star education thrusts to the galaxy passage
An important factor of influence on the star formation in our milky way have now identified astronomers to Tomás Ruiz-Lara from the astrophysical Institute of the Canary Islands, Tenerife. “From existing models, we know that the Sagittarius dwarf galaxy is plunged three times into the milky – just six billion years, two billion years ago and before about a billion years,” explains Ruiz-Lara. Currently, this dwarf elliptical galaxy is about 50,000 light years from the milky way centre and includes around a billion, mostly of old stars. The theory is that through moving their collisions from above or below by the stars in our galaxy’s disk. To find out, what were the consequences of these passages, analyzed, astronomers using data from the Gaia satellite of ESA, created a star catalogue through the eyes and the luminosity, distances, temperature and colors of stars in a radius of about 6500 light years of the sun.
From this data were able to close the astronomers on the age and the date of origin of these stars. “We have the times, in which we found enhanced star formation, with which compared, to please the Sagittarius dwarf galaxy in the milky way,” explained the astronomer. In fact, they noted a connection: “We found three periods of strong star formation, which had 5.7 billion years ago, before 1.9 billion years and a billion years ago its peak,” says Ruiz-Lara. “This corresponds with the time that the Sagittarius galaxy through the disk of the milky way through the be moved.” These collisions could have added, therefore, the Gas and dust in our galaxy in motion, that it came in many places to the Collapse of gas clouds, and thus to the birth of new stars. “This is the first Time that we have broken down the star formation history of the milky way in such detail,” says the study, involved in the Gaia project scientist Timo Prusti.
the impetus for the formation of our sun?
Especially exciting could be the first of these collisions, approximately 5.7 billion years ago. Because it took place shortly before the star educational thrust, with the front of around 4.7 billion years ago our sun was born. “The sun formed at the time when the star formed in the Wake of the first Passage of Sagittarius,” says Ruiz-Lara’s colleague Carme Gallart. “We do not know whether the Gas and dust cloud in which the sun arose, collapsed in the Wake of the Sagittarius-Passage or not. But it is a realistic scenario, because the age of the sun fits well to a star that has arisen as a result of this collision.” We could, therefore, owe our existence, ultimately, only this galactic pile-up, with our smaller neighbours. “Sagittarius has not influenced, therefore, only the structure and stellar dynamics of our milky way, it has also contributed to the fact that it is grown,” says Gallart.
For the Sagittarius dwarf galaxy, however, these repeated collisions were far less positive. Because the observations indicate that they lost their first Passage, the majority of the gas. As a result, the supply of materials for new stars and the star formation in the dwarf galaxy was missing received a strong shock, such as the astronomers explain. With each Passage of Sagittarius lost in addition, further Gas and was smaller.
source: Tomás Ruiz-Lara (Instituto de Astrofísica de Canarias, Tenerife) et al., Nature, Astronomy, doi: 10.1038/s41550-020-1097-0
*the thrusts of The article “star formation in the milky way” published by Wissenschaft.de. Contact with the executives here.
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