The shape and size of our galaxy, the Milky Way, might be much different from what was previously believed.
New research suggests the Milky Way is at least 50 percent larger than past estimates have shown and is contoured into several concentric "ripples," Rensselaer Polytechnic Institute reported.
"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," said Heidi Newberg, professor of physics, applied physics, and astronomy in the Rensselaer School of Science. "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."
Features that were previously identified as rings are now believed to actually be part of the galactic disk, making the Milky Way up to 150,000 light years wider than scientists thought it was.
"Going into the research, astronomers had observed that the number of Milky Way stars diminishes rapidly about 50,000 light years from the center of the galaxy, and then a ring of stars appears at about 60,000 light years from the center," said Yan Xu, a scientist at the National Astronomical Observatories of China. "What we see now is that this apparent ring is actually a ripple in the disk. And it may well be that there are more ripples further out which we have not yet seen."
To make their findings, the researchers used data from the Sloan Digital Sky Survey (SDSS), revealing an "an oscillating asymmetry in the main sequence star counts on either side of the galactic plane," that moved from the Sun to the galactic center. The research backs up and builds upon research conducted in 2002 in which Newberg spotted the existence of the "Monoceros Ring." This is an "over-density" of stars at the outer edges of the Milky Way. At the time, the researcher noticed a second over-density of stars between the Monoceros Ring and the sun, but was unable to study it in more detail.
In this new study the researchers took another look at the data and noticed four anomalies, or "ripples," in the galaxy. These findings also support the idea that a dwarf galaxy or lump of dark matter passing through the Milky Way could produce this type of rippling effect.
"It's very similar to what would happen if you throw a pebble into still water - the waves will radiate out from the point of impact," Newberg said. "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. 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 findings were published in a recent edition of The Astrophysical Journal.
