First 3D map of Milky Way reveals warped galaxy

The Milky Way Is Totally Twisted

At the center of the Milky Way is a supermassive black hole, surrounded by billions of stars and invisible "dark matter", which can't be seen directly but exerts a gravitational pull that helps keep the galaxy intact.

Astronomers looked at data from the WISE survey of infrared stars and noted that it contained a large sample of Cepheids.

Burning their fuel quickly, those pulsating stars that live fast and die young are 100,000 times brighter than the Sun. Their mapping efforts revealed the warped nature of the galaxy's far outer disk.

Prof de Grijs said: "Somewhat to our surprise, we found in 3D our collection of 1,339 Cepheid stars and the Milky Way's gas disc follow each other closely".

Without accurate measures of the distance between the sun and stars in the Milky Way's outer regions, it's hard to determine the precise shape of the galaxy and its gas disk.

While the recent study focused on making the map, not explaining it, the authors hypothesize that as the Milky Way's inner disk of stars rotates, it drags on the outer disk as well, distorting the flat spiral.

The Milky Way really is warped - like a bent old vinyl record, according to new research. Researchers from the Macquarie University in Australia and the Chinese Academy of Sciences have found for the first time that our solar system is anything but stable and flat. They used 1,339 pulsating stars - young, newly catalogued stars bigger and brighter than our sun - to map the galaxy's shape.

"It is notoriously hard to determine distances from the Sun to parts of the Milky Way's outer gas disk without having a clear idea of what that disk actually looks like", said Chinese Academy of Sciences astronomer Dr. Xiaodian Chen, lead author of the study. Just like a goldfish can't see its bowl from the outside, our position in the universe means we can't see our home galaxy, the Milky Way, as the rest of the universe sees it.

NAOC found that this galactic game of schoolyard bullying forms the warped S-shape of our galaxy.

"This new morphology provides a crucial updated map for studies of our galaxy's stellar motions and the origins of the Milky Way's disk", said Licai Deng, senior researcher at the Chinese Academy of Sciences. A dozen other galaxies had previously been shown to display similar warping, the researchers reported today (Feb. 4) in the journal Nature Astronomy. Since hydrogen atoms in the far outer disk are no longer confined to a thin plane, they get warped.

Co-author Dr Liu Chao, also of the Chinese Academy of Sciences, said: "Combining our results with those other observations, we concluded the Milky Way's warped spiral pattern is most likely caused by "torques" - or rotational forcing - by the massive inner disk".



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