Spinning Milky Way Galaxy's Halo Discovered

The Milky Way galaxy has a halo and as astronomers found out, the hot gas is spinning in the same direction and almost at the same speed as the galaxy's disk, the same disk that holds the stars, planets, gas and dust.

Astronomers from the University of Michigan's College of Literature, Science and the Arts (LSA) discovered the spinning of the halo and it is expected to add significant information on how stars, planets, galaxies and other celestial bodies form through assembly of atoms.

"This flies in the face of expectations," Edmund Hodges-Kluck, assistant research scientist said in a statement. "People just assumed that the disk of the Milky Way spins while this enormous reservoir of hot gas is stationary - but that is wrong. This hot gas reservoir is rotating as well, just not quite as fast as the disk," Hodges-Kluck added.

The research was published in the Astrophysical Journal and was funded by NASA using the European Space Agency's (ESA) telescope. The study focused on the Milky Way hot gaseous halo that is a few times larger that the galaxy disk made up of ionized plasma. To arrive on their findings, the astronomers studied the shift in the wavelength of light around the sky by using lines of hot oxygen. This is the process responsible for discovering a momentous feat when they found out that the halo was spinning based on its patterns. The halo is said to spin at about 400,000 mph while the disk spins at 540,000 mph.

Because motion produces a shift in the wavelength of light, the U-M researchers measured such shifts around the sky using lines of very hot oxygen.

What they found was groundbreaking: The line shifts measured by the researchers show that the galaxy's halo spins in the same direction as the disk of the Milky Way and at a similar speed--about 400,000 mph for the halo versus 540,000 mph for the disk. "The rotation of the hot halo is an incredible clue to how the Milky Way formed," said Hodges Kluck in a statement.

This is an important discovery in understanding the origin of galaxies such as the Milky Way. Experts believe that the hot gas on the halo is vital in the formation of galaxies.