The Milky Way in a twist

James Marshall
February 5, 2019

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).

Scientists have known since the 1950s that the spiral-shaped Milky Way's disk is warped, bending by thousands of light-years at its outskirts.

But the research solidifies something that you might not know about our galaxy-if you picture it as a lovely, flat spiral akin to images of Andromeda, it's time to repaint that picture as a floppy, curved disk of stars and gas.

The scientists updated a 3D map of the Milky Way using 1,339 large pulsating stars, each up to 100,000 times brighter than the sun.

The stars used to create the map are called classical Cepheids.

From afar, the Milky Way appears like a thin rotating disk of stars, orbiting the center every few hundred million years.

"We concluded that the Milky Way's warped spiral pattern is most likely caused by "torques" - or rotational forcing - by the massive inner disk", says Dr. Liu Chao, senior researcher and co-author of the paper.

"We found that the S-like stellar disk is warped in a progressively twisted spiral pattern", de Grijs said.

This reminded the team of earlier observations of a dozen other galaxies which also showed such progressively twisted spiral patterns.

This is where hundreds of billions of stars can be found - together with a huge mass of dark matter.

An worldwide team of astronomers have discovered that the Milky Way's disc of stars becomes increasingly "warped" and twisted the further away the stars are from the galaxy's center.

This is the mysterious invisible material that provides the gravitational "glue" that holds galaxies together. 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. You can see their final plot in the video below, published in Nature Astronomy.

One researcher not involved with this study, Annie Robin, astrophysicist at the Observatoire de Besançon in France, thought the difference between the hydrogen and the Cepheid data was quite surprising, though the team's results did agree with previous papers.

IAC researcher Jonay González Hernández said: 'Theory predicts that these stars could form just after, and using material from, the first supernovae, whose progenitors were the first massive stars in the Galaxy'.

Other reports by Click Lancashire

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