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A new study has revealed that the Milky Way is not a tidy and flat disk - it's seriously distorted at the edges. Often we compare our galaxy to our neighbor, Andromeda. Andromeda is (probably) larger than the Milky Way, but both galaxies are very large, spiral, and of the same age.

As we live within the Milky Way, we cannot really observe its full form. But given what we know about galaxies in general, it has so far made sense to think that the Milky Way probably looks a bit like Andromeda, with its neat, ordered spiral arms.

Now, astrophysicists have discovered that the further away from the galactic center, the more distorted and twisted the disc of the Milky Way becomes. Your galactic plane is not a straight line; instead, it looks a bit more like an elongated S. The discovery came thanks to some new distance measurements of stars in the outer regions of the galaxy.

"It is notoriously difficult to determine distances from the Sun to parts of the outer gas disk of the Milky Way without having a clear idea of ​​what this disk actually is," said astronomer Xiaodian Chen of the National Astronomical Observatory of the Chinese Academy of Sciences.

One way is to use a star type called the Cepheid variable. These are very bright stars pulsating with a precise frequency, which allows astronomers to calculate their absolute magnitude. This in turn allows the distances of these stars to be calculated. In the optical spectrum, dust and gas between us and the star can disrupt the precise determination of brightness, which means that there is a bit of uncertainty in the resulting distance calculations.


But infrared radiation can penetrate the dust, which contributes to a more accurate result - and that's what scientists used. "We used a new catalog of infrared observations obtained with the WISE space observatory to reduce the effects of dust and determine distances for our Cepheids with a margin of error of 3 to 5% - an unprecedented precision so far," said astrophysicist Richard Grijs of Macquarie University in Australia.

"Combined with their apparent locations in the sky, we constructed a three-dimensional map of the Milky Way, traced by these Cepheids, which we compared with the gas distribution. Both seemed to deviate from a flat disk, "he concluded.

It is a result that gives us a better understanding of the three-dimensional and dynamic structure of our galaxy, and will allow us to establish an upper limit on the amount and distribution of matter in the galaxy. It will also help us better understand the relationship and interactions of the Milky Way with its satellite galaxies, specifically the Magellanic Clouds. [ ScienceAlert ]

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