Our Milky Way galaxy isn’t a neat, flat disc of stars – it’s actually being warped out of shape by its inner disc, scientists say.
Chinese scientists created the first accurate 3D map of the Milky Way using stars known as classical Cepheids – and found it’s like a warped S shape, being distorted by its own spin.
Prof. Richard de Grijs from Macquarie University in Sydney said, ‘Somewhat to our surprise, we found that in 3-D, 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.
‘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.’
Classical Cepheids are young stars that are some four to 20 times as massive as the sun and up to 100,000 times as bright.
Combined with a Cepheid’s observed brightness, its pulsation period can be used to obtain a highly reliable distance.
Dr. Liu Chao, senior researcher and co-author of the paper said that the researchers observed other ‘warped’ spiral galaxies.
He said, ‘Combining our results with those other observations, we concluded that the Milky Way’s warped spiral pattern is most likely caused by torques—or rotational forcing—by the massive inner disk.’