The Milky Way galaxy is at least 50 per cent larger than commonly estimated, according to a new study which found that the galactic disk is contoured into several concentric ripples.
The research, conducted by an international team led by Professor Heidi Jo Newberg at the Rensselaer Polytechnic Institute in the US, revisited astronomical data from the Sloan Digital Sky Survey which, in 2002, established the presence of a bulging ring of stars beyond the known plane of the Milky Way.
“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,” Newburg said.
The findings show that the features previously identified as rings are actually part of the galactic disk, extending the known width of the Milky Way from 100,000 light years across to 150,000 light years, said Yan Xu, a scientist at the National Astronomical Observatories of China, former visiting scientist at Rensselaer, and lead author of the paper.
“Going into the research, astronomers had observed that the number of Milky Way stars diminishes rapidly about 50,000 light years from the centre of the galaxy, and then a ring of stars appears at about 60,000 light years from the centre,” said Xu.
“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,” Xu added.
The research was published in the Astrophysical Journal.