Milky Way Galaxy’s “Halo” spins along with the galaxy
The halo was thought to be still for many years now. In a new research, astronomers found that the hot gas in the halo of the Milky Way galaxy is spinning continuously in the same direction as the two spiral arms of the galaxies are spinning. Now for the first time, astronomers have measured the speed of the halo and found it is spinning too, at a ‘dizzying’ speed. The spinning speed measured for the halo is 400,000 mph while for the disk is 540,000mph.
It was measured by observing shifts in wavelengths of light, researchers measured the shifts around the sky using very hot oxygen, which would have caused due motion. The study was conducted at University of Michigan’s College of Literature, Science and the Arts (LSA).
Halo is composed of ionized plasma and is several times larger than the disk of Milky Way.
It was assumed that Milky Way spins around the hot reservoir of hot gas whereas the reservoir is stationary. The rotation of Halo could provide an incredible clue of how Milky Way is formed. “It tells us that this hot atmosphere is the original source of a lot of the matter in the disk” said Mr Hodges Kluck.
According to scientists, 80 percent of the matter in the universe exist in the form of dark matter that can only be detected by gravitational pull for now, as almost all galaxies, including the Milky Way, seem to lack most of the matter that they otherwise would expect to find. Out of rest of the 20 percent matter, some was also disappearing and was found to be in halo. Now, that they have learned about its speed and direction, they can find out that how the matter went to the halo in the first place.
The new NASA funded research used data gathered by XMM-Newton, an Esa telescope, and was recently published in the Astrophysical Journal.