Neighboring galaxies steal stars from the milky Way, astronomers have found

© Eatec the artist presented himself a star escaping from the milky WayNeighboring galaxies steal stars from the milky Way, astronomers have found© ESA

. Some of the stars on the outskirts of the milky Way was there not as a result of the absorption of the remains of dwarf galaxies, with whom he recently faced as a result of «theft» of his shining like the satellites of our Galaxy, according to a paper published in the journal Nature.

«These stars aren’t just helping us to know what happened to the disk of the Galaxy in the distant past, they also allow us to predict what will happen to her in the future. Watching them gives us a whole new window into the life and work of the Universe,» said Catherine Johnston (Kathryn Johnston) of Columbia University in new York (USA).

The milky Way is in the intergalactic void is not alone, but in the company of a large retinue of dwarf galaxies, most of which we cannot see because of their extreme dullness. Today scientists believe, many of these dwarfs periodically moving closer to our Galaxy, the final «traces» which are the so-called star streams.

They look like a kind of «tape» of stars, not related to each other by gravity, orbiting the center of the milky Way over and under the disk, where the Earth, Sun and nearly all other stars. Stellar streams as today the astronomers believe, are the remnants of globular clusters or dwarf galaxies, once torn to pieces and absorbed the Milky Way in the distant past.

During these apocalyptic events as astronomers figured out six years ago during the observation of the so-called «ring of the unicorn», one of the most visible stellar streams of the milky Way «steals» almost all the dark matter have torn them galaxies. As a result, they fall apart and turn into those tapes that we can see in the night sky above the disk of the Galaxy.

Johnston and her colleagues found that not all the stars in these bands and rings are part of the victims of galaxies, watching one of the distant structures of this kind, which the astronomers called the «clouds of Andromeda-Triangle». It is located at the junction of the constellations of Andromeda and Triangle removed from the center of the Galaxy is about 60 thousand light years.

Scientists have tried to uncover the history of the formation of these streams of stars, watching the two types of lights – the elderly red giants, nearly exhausted their supplies of hydrogen, and variable stars of the RR Lyra class, periodically changing its brightness.

As Johnston explains, those and other stars have unusual physical properties that depend only on the sizes of these bodies and how much light they produce, which allows astronomers to accurately calculate the distance to them to determine their age and speed.

Guided by these ideas, her team calculated the speed of motion of 14 stars located in the clouds of Andromeda-Triangle, and unexpectedly found that they could not get to the outskirts of the milky Way, if they were born inside the dwarf galaxy, a recently deceased during a «cosmic accident».

This prevents two things – an unusual speed and direction of motion of these bodies, and that among them much more class stars RR Lyra than red giants, which is not typical for dwarf satellites of the Galaxy. In addition, the analysis of their spectra showed that chemical composition they are much closer to the lights of the milky Way than to the potential «runaways» from its neighbors.

How could they be on the outskirts of the Galaxy? Scientists believe that some dwarf are destroyed when approaching the Milky Way far not at once – some of them experiencing such a «rendezvous» and drags part of the stars located on its outskirts, but also in the Central parts of disk Galaxies.

«I’m glad we managed to find the last of these «galactic wars», which confirms that our galaxy continuously «bombard» its neighbors. In the past, colleagues have focused their efforts on studying how the milky Way is being torn apart by their neighbors. We were very interested to find traces of the fact that dwarf galaxies may hurt to beat their «big neighbor,» concludes Johnston.