Milky Way isn't a flat disk, it's corrugated

TROY, N.M., March 11 (UPI) -- According to a new study by a team of international astronomers, the Milky Way's galactic disk resembles the undulating ripples seen after a pebble is tossed into a pond. In other words, it's not flat -- it's corrugated, like a steel roof.

The study, led by Heidi Jo Newberg, an astronomer at the Rensselaer Polytechnic Institute, in Troy, N.Y., is a reinterpretation of data collected as part of the Sloan Digital Sky Survey. The 2012 survey helped astronomers locate a ring of stars, existing just off the plane of the Milk Way's disk.

But the latest study suggests the ring of stars isn't distinct from the galactic disk, but part of it -- and that there are three other ripples just like it. The analysis also posits that the width of the Milky Way is not 100,000 light-years across, but 150,000.

"In essence, what we found is that the disk of the Milky Way isn't just a disk of stars in a flat plane -- it's corrugated," Newberg explained in a press release. "As it radiates outward from the sun, we see at least four ripples in the disk of the Milky Way. While we can only look at part of the galaxy with this data, we assume that this pattern is going to be found throughout the disk."

Researchers say the observed oscillations match up with previous research models, including one theory that predicted the results of a dwarf galaxy or concentration of dark matter passing through the Milky Way.

"If a dwarf galaxy goes through the disk, it would gravitationally pull the disk up as it comes in, and pull the disk down as it goes through, and this will set up a wave pattern that propagates outward," Newberg explained. "If you view this in the context of other research that's emerged in the past two to three years, you start to see a picture is forming."

The new study was published Wednesday in the Astrophysical Journal.