Our Milky Way galaxy is truly warped, at least around edges

Rodiano Bonacci
Febbraio 8, 2019

"This research provides a crucial updated map for studies of our galaxy's stellar motions and the origins of the Milky Way's disk", added Licai Deng, also from the Chinese Academy of Sciences. These stars providing high distance accuracy were used as primary distance indicators to develop an intuitive and accurate three-dimensional picture of the galaxy.

The shape of the Milky Way - our home galaxy - isn't exactly what we've always assumed it was.

The Milky Way's disk of stars is not stable or flat but instead becomes increasingly "warped" and twisted far away from the galaxy's centre, according to astronomers. The newly-created and most accurate 3D map of our galaxy reveals that it's warped and twisted, and even more fascinating.

"It is notoriously hard to determine distances from the Sun to parts of the Milky Way's outer gas disc without having a clear idea of what that disc actually looks like", study lead author Chen Xiaodian from the research team of Chinese Academy of Sciences explained.

'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'.

Researchers established a robust Galactic disc model based on 1,339 variable stars which are four to 20 times larger than the Sun, and up to 100,000 times more luminous. However, their massive size and brightness aren't without flaw, indicating that they live fast lives and end them pretty young, as they use all the gas as fuel. In astronomical units, a few million years is pretty young.

They show day- to month-long pulsations, which are observed as changes in their brightness.

"It was very well known already for a number of decades that if you look at our Milky Way galaxy from the side it looks like a flat pancake", study co-author Professor Richard de Grijs from Macquarie University told Xinhua on Wednesday.

"Somewhat to our surprise, we found that in 3D our collection of 1339 Cepheid stars and the Milky Way's gas disc follow each other closely".

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