A new map of the Milky Way Galaxy reveals its true shape. Instead of a flat disk, home is actually more warped and look more like an elongated "S."
A team of astronomers from the Macquarie University in Australia and the Chinese Academy of Sciences have mapped out the Milky Way using 1,339 "standard stars." The effort provides an updated look at "home," including its stellar motions.
A New Look At The Milky Way Galaxy
Because Earth is well within the Milky Way, scientists have never really observed its true shape. They assumed that like the neighboring Andromeda, Milky Way is a neat flat disk with orderly spiral arms.
However, that is not the case. In a paper that appears in the journal Nature Astronomy, astronomers revealed that the Milky Way becomes increasingly "warped" and "twisted" the further away the stars are from the center.
In the past few decades, there had been signs that point to a more warped galactic disk. However, determining the Milky Way's real shape is like "standing in a Sydney garden and trying to determine the shape of Australia" as explained by the astronomers.
To create the map, the team used a type of star called a Cepheid variable. These are bright stars that pulsate periodically, allowing scientists to use them as "cosmic yardsticks" to measure objects that are far away.
"We used a new catalog of infrared observations obtained with the WISE space observatory to reduce the effects of dust and determine the distances to our Cepheids with uncertainties of less than 3 to 5 percent — that's an unprecedented accuracy to date," stated Richard de Grijs, an astrophysicist from Macquarie University and an author of the paper. "Combined with their apparent locations in the sky, we constructed a three-dimensional map of the Milky Way as traced by these Cepheids, which we compared with the gas distribution."
The team explained that the warped shape of the Milky Way is caused by the massive inner disk forcing the outer disk to follow its rotation. However, the rotation of the outer disk lags behind.
De Grijs added that it is not unusual for galaxies like the Milky Way to appear warped around the edges. Scientists previously observed a dozen other galaxies that twist and warp in the outer regions. However, what makes their discovery interesting is the appearance of young stars.
Unlocking New Details About The Home Galaxy
Unlike the Andromeda Galaxy, which can be observed through a telescope, studying the Milky Way Galaxy is a challenge. The team hopes that the updated map of the galaxy will inform about the motions and origins of the Milky Way.
They also believe that their work will help determine the dark matter distribution within this galaxy.
