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Astronomers Made a Groundbreaking Discovery Regarding Milky Way's Hot Gaseous Halo

Jul 26, 2016 06:19 AM EDT
Milky Way Halo
Our Milky Way galaxy and its small companions are surrounded by a giant halo of million-degree gas (seen in blue in this artists' rendition) that is only visible to X-ray telescopes in space. University of Michigan astronomers discovered that this massive hot halo spins in the same direction as the Milky Way disk and at a comparable speed.
(Photo : NASA/CXC/M.Weiss/Ohio State/A Gupta et al)

A new research funded by NASA revealed that the hot gaseous halo of Milky Way Galaxy is actually spinning at the same direction and at comparable speed as the galaxy's disk.

The discovery, published in the Astrophysical Journal, was made by astronomers at the University of Michigan's College of Literature, Science and Arts using the archival data obtained from the XMM-Newton of the European Space Agency.

"This flies in the face of expectations," explained Edmund Hodges-Kluck, assistant research scientist, 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."

For the research, the astronomers measured the shifts in the wavelengths of light, which is produced by motion, around the sky using lines of very hot oxygen. They then discovered that the galaxy's hot gaseous halo is also spinning in the same direction as the Milky Way at 400,000 mph, which is comparable to the speed of the disk that spins at 540,000 mph.

The new groundbreaking discovery could pave way to the better understanding on how the galaxy is formed. Astronomers have been long baffled why they could not find most of the matter they thought they would find in the disk of the galaxies.

They believe that 80 percent of the matter in the universe is what they called as dark matter, which can only be detected by its gravitational pull. However, the remaining 20 percent of normal matter is still missing from the galaxy disk. Previous researchers found these missing matters in the galaxy's halo. By learning the direction and speed of the spinning halo, researchers can now determine how the matter got to where they are now and the rate at which they are expected to settle in the galaxy.

"Now that we know about the rotation, theorists will begin to use this to learn how our Milky Way galaxy formed - and its eventual destiny," commented Joel Bregman, a U-M LSA professor of astronomy, in a press release. "We can use this discovery to learn so much more - the rotation of this hot halo will be a big topic of future X-ray spectrographs."

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