Milky way is warped | Not flat disk shaped

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We all studied that our Galaxy milky way and all other Galaxies are flat disk shaped and indeed that was true until New studies found that Galaxies like milky way are warped not flat disk shaped .

The Milky Way galaxy, perturbed by the tidal interaction with a dwarf galaxy, as predicted by N-body simulations. Credit: T. Mueller/C. Laporte/NASA/JPL-Caletch
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The Milky Way galaxy, perturbed by the tidal interaction with a dwarf galaxy, as predicted by N-body simulations. Credit: T. Mueller/C. Laporte/NASA/JPL-Caletch

Yes, you heard right ,our Galaxy is warped but how do we know and what made it warped let’s answer all these questions .

How do we get that milky way is not flat ?

For centuries astronomers were trying to calculate the dimensions of milky way galaxy like it’s total length , structure on the idea that milky way is flat disk shaped but always yielded inaccurate results which leads the scientists to find out the true model of the Galaxy.

A recent study by a team of astronomers from National Astronomical Observatories of Chinese Academy of Sciences (NAOC) has shown that the Milky Way’s disk is not flat (as previously thought). Based on their findings, it appears that the Milky Way becomes increasingly warped and twisted the farther away one ventures from the core.

The study that details their findings recently appeared in the scientific journal Nature, titled “An intuitive 3D map of the Galactic warp’s precession traced by classical Cepheids.” The study was led by Xiaodian Chen of the NAOC’s Key Laboratory for Optical Astronomy and included members from the Kavli Institute for Astronomy and Astrophysics at Peking University and China West Normal University.

Image showing a warped galaxy
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To break it down, galaxies like the Milky Way consists of thin disks of stars that orbit around a central bulge once every few hundred million years. In this bulge, the gravitational force of hundreds of billions of stars and dark matter hold the galaxy’s matter and gas together. However, in the far outer regions of the galaxy, the hydrogen atoms making up most of the gas disk are no longer confined to a thin plane.

The discovery that the milky way galaxy is warped and not flat is possible by classic cephieds which are new catalogue of periodic variable stars .

What are these Classic Cephieds ?

Classical Cephieds are a subclass of Cephied variables, a type of star that is noted for the way it pulsates regularly, varying in both diameter and temperature. This produces changes in brightness that are predictable in terms of period and amplitude and makes them highly useful for measuring galactic and cosmic distances.

Classical Cepheids are a particular type of young yellow bright giant and supergiant that are 4 to 20 times as massive as our Sun and up to 100,000 times as luminous. This implies that they have short lifespans that sometimes last only a few million years before exhausting their fuel. They also experience pulsations that can last days or even a month, which makes them very reliable for measuring the distances to other galaxies.

As Dr. Shu Wang, of the Kavli Institute for Astronomy and Astrophysics and co-author on the paper, stated:

“Much of our Milky Way is hidden by dust, which makes it difficult to measure the distances to stars. Fortunately, observations at long infrared wavelengths can circumvent this problem.”

For the sake of their study, the team established a 3D galactic disk model based on the positions of 1,339 Classical Cephieds. From this, they were able to provide strong evidence that the galactic disk is not in line with the galactic center. In fact, when viewed from above, the Milky Way’s disk would appear S-shaped, with one side curving up and the other curving down.

The Milky Way galaxy, perturbed by the tidal interaction with a dwarf galaxy, as predicted by N-body simulations. Credit: T. Mueller/C. Laporte/NASA/JPL-Caletch
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3D distribution of the classical Cephied variable stars in the Milky Way’s warped disk (red and blue points) centered on the location of the sun (shown as a large orange symbol). Image via Science in Public.

What makes galaxy warped shape ?

The warped shape of a galaxy is caused by instabilities on the disk’s edge, where the galaxy’s gravitational forces are weaker and objects are more prone to bending and twisting. It’s a common phenomenon for spiral galaxies.

D’Onghia does note, however, that the origin of the warp still needs a more detailed explanation, especially since the hydrogen gas still seems to twist more rigorously then the stars do. “It could be due to torques exerted by a large satellite galaxy like the Large Magellanic Cloud, or the Sagittarius dwarf galaxy that impacted the Milky Way disk not long ago,” she says. “It could be by torques exerted by the inner disk, as the authors claim. [They] do not really explore the different ways to generate the warp as compared to the data.”


About 85 percent of the universe is thought to be made of dark matter. We can’t directly observe it, but its presence is implied because it gravitationally affects the movements of other celestial structures whirring around through outer space. “We know we need it to explain the motions of the stars in the Milky Way,” says de Grijs. Understanding the shape of the Milky Way means we can get a better handle on where that dark matter is located in the galaxy.

The warped structure of the milky way galaxy could unfold the mysteries of the universe and explain the formation of milky way galaxy.

Hence explained Milky way is warped | Not flat disk shaped

Author: Sushant pal

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