Most detailed map of mysterious hydrogen clouds created

Australian scientists have created the most detailed map ever of clouds of high-velocity gas in the universe around us, and found that it covers at least 13 per cent of the sky.
The map covers the entire sky and shows curious clouds of neutral hydrogen gas that are moving at a different speed to the normal rotation of the Milky Way.
"These gas clouds are moving towards or away from us at speeds of up to a few hundred kilometres per second. They are clearly separate objects," said Tobias Westmeier, from The University of Western Australia.
The map, published in the journal Monthly Notices of the Royal Astronomical Society, was compiled by taking a picture of the sky and masking out gas that is moving at the same pace as the Milky Way to show the location of gas travelling at a different speed.

It is the most sensitive and highest resolution all-sky map of high-velocity clouds ever created.
It shows the gas in spectacular detail, revealing never before seen filaments, branches and clumps within the clouds.

"It is something that wasn't really visible in the past, and it could provide new clues about the origin of these clouds and the physical conditions within them," Westmeier said.
The astronomers had proposed several hypotheses about where high-velocity clouds come from.
"We know for certain the origin of one of the long trails of gas, known as the Magellanic Stream, because it seems to be connected to the Large and Small Magellanic Clouds," he said.

"The clouds are very close to the Milky Way, within about 30,000 light years of the disc," he added.