But the known galaxies in the area can not quite explain the direction and speed of the Milky Way movement, the researchers realized. Therefore, they assumed that there could be another galaxy or even entire galaxy systems in the hidden area behind the center of the Milky Way galaxy. The researchers therefore calculated the mass and distance of these hypothetical star systems in order to reconcile the Milky Way movement on the basis of the galaxy distribution and the background radiation.
According to the calculations, behind the center of the Milky Way galaxy could be a similarly large galaxy only three million light-years away. Alternatively galaxy clusters in 70 million light-years distance would be conceivable. However, other astronomers such as Brent Tully of the University of Hawaii in Honolulu believe that a twin system to explain the Milky Way movement is not necessary. Far beyond the galaxies considered by the researchers Loeb and Narayan, there are still large galaxy clusters, such as the Shapley supercluster 650 million light-years away, which also attract the Milky Way. If there were star systems just beyond the Milky Way, astronomers would have discovered them long ago, Tully says.New Scientist, online service ddp / science.de? Martin Schäfer advertisement