Published: Wed, February 06, 2019
Research | By Raquel Erickson

Astronomers Reveal a Warped and Twisted Milky Way

Astronomers Reveal a Warped and Twisted Milky Way

They have found that the Milky Way is not exactly as artist's impressions might have you believe - it's actually twisted and warped, bending at the edges. Instead of lying in a flat plane, the galaxy takes on a bit of a twisted "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 Xiaodian Chen, a researcher at the Chinese Academy of Sciences in Beijing.

An global 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. 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.

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.

The paper, published in Nature Astronomy on February 4, details work by Australian and Chinese astronomers to examine the classical "Cepheids" - a collection of huge, young stars in the Milky Way that can be up to 100,000 times brighter than the sun.

They show day- to month-long pulsations, which are observed as changes in their brightness. Using these pulses in brightness, scientists can detect the distance of these stars within 3 percent to 5 percent accuracy, study lead author Xiaodian Chen, a researcher at the National Astronomical Observatories, said in the statement. Their mapping efforts revealed the warped nature of the galaxy's far outer disk.

The Milky Way isn't alone. Scientists have observed other similarly warped galactic disks, and the team inferred that the rotational forces from the inner galaxy were producing the warped shape. We know the Milky Way is a spiral galaxy - a thin disk of a hundred billion stars that circle around a huge supermassive black hole at the galaxy's centre. Astronomers from Macquarie University and the Chinese Academy of Sciences have used 1339 "standard" stars to map the real shape of our home galaxy in a paper published in Nature Astronomy today.


Dr Deng said: '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'.

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 the strictures of strong gravity, the outer gas disk's hydrogen atoms form an S-like, warped structure - a twist.

A newly discovered star is thought to be one of the oldest in the Milky Way.

"We would need to do (numerical) simulations of a realistic galaxy embedded in a dark matter halo to see if we can reproduce the observations and figure out how this came about", says de Grijs.

Scientists at the Instituto de Astrofísica de Canarias (IAC) in Spain believe that it might have formed about 300 million years after the "Big Bang".

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