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takyon [soylentnews.org] writes:

The Milky Way in a twist [eurekalert.org]

Our Milky Way galaxy's disk of stars is anything but stable and flat. Instead, it becomes increasingly 'warped' and twisted far away from the Milky Way's center, according to astronomers from National Astronomical Observatories of Chinese Academy of Sciences (NAOC).

From a great distance, our galaxy would look like a thin disk of stars that orbit once every few hundred million years around its central region, where hundreds of billions of stars, together with a huge mass of dark matter, provide the gravitational 'glue' to hold it all together.

But the pull of gravity becomes weaker far away from the Milky Way's inner regions. In the galaxy's far outer disk, the hydrogen atoms making up most of the Milky Way's gas disk are no longer confined to a thin plane, but they give the disk an S-like warped appearance.

[...] "Somewhat to our surprise, we found that in 3D our collection of 1339 Cepheid stars and the Milky Way's gas disk follow each other closely. This offers new insights into the formation of our home galaxy," says Prof. Richard de Grijs from Macquarie University in Sydney, Australia, and senior co-author of the paper. "Perhaps more importantly, in the Milky Way's outer regions, we found that the S-like stellar disk is warped in a progressively twisted spiral pattern."

An intuitive 3D map of the Galactic warp's precession traced by classical Cepheids [nature.com] (DOI: 10.1038/s41550-018-0686-7) (DX [doi.org])

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