New research made by scientists at Harvard shows that our galaxy may actually be even more complex than expected, especially when it comes to interactions with its neighbors. Thus, it seems that the Milky Way has a habit of "stealing" stars from smaller galaxies found in its vicinity. This resulted in the development impressive streams of stars, which measure more than one million light-years in length.
Milky Way, Stealing Stars
Due to technological advancements, scientists are now able to make better observations that would have been considered inconceivable before. Thus, they were able to find out some very interesting things about what happens at the edge of our galaxy and the way galaxies interact with each other.
The researchers at Harvard analyzed the eleven farthest known stars in the Milky Way and realized five of them had been "stolen" from a neighboring dwarf galaxy called Sagittarius. Located 300,000 light-years from Earth, the stars seem to be part of a long stream of stars that extends a million light-years across space. They are located outside the reach of our galaxy's spiral disk, and researchers believe they are part of a slow but steady flow of cosmic material being pulled from the Sagittarius dwarf.
To understand just how much that distance is, imagine the stream is ten times longer than the width of the Milky Way. And it seems more discoveries are expected to follow.
In order to better understand the phenomenon, the researchers created a model based on the rotation of the dwarf galaxy around ours.
During its several complete loops around the Milky Way, the Sagittarius lost some of its stars as it approached the larger galaxy.
The scientists used computer models to replicate the phenomenon during the last 8 billion years, varying factors such as the angle of approach and the initial velocity in order to match current observations. The results made the scientists very excited, especially as they were confirmed by observations.
According to the models, the Sagittarius dwarf initially weighed ten billion times more than our sun, being 100 times lighter than the Milky Way. However, as time passed, the smaller galaxy lost one-third of its stars and nine-tenths of its dark matter.
This resulted in three very large streams of stars that go as far as 1 million light years from the center of our galaxy, reaching its edge. These streams are among the biggest structures that can be observed from Earth. Moreover, five of the eleven most distant stars known to us match the information provided by the models, so they are among those "captured" from the smaller galaxy. The other six stars may have been attracted in the same manner, but from other dwarf galaxies.
The Three Streams Of Stars
So far, only one of the three streams of stars has been observed properly, but it is believed the other two will soon be mapped as well. By using advanced instruments like the Large Synoptic Survey Telescope, researchers hope they will get a better understanding of our galaxy, its origin, and its future as well.
