BEIJING, Aug. 13 (Xinhua) -- Chinese researchers have identified widespread corrugated structures in the Milky Way for the first time, offering fresh observational evidence for understanding the galaxy's three-dimensional architecture and dynamic evolution.
The finding, from a team at the Purple Mountain Observatory (PMO) under the Chinese Academy of Sciences, was published on Aug. 7 in the journal Nature Astronomy.
The Milky Way's overall shape resembles a warped record, with one side bent upward and the other downward, a large-scale deformation known as the "warp." However, systematic observations and quantitative studies of finer vertical structures within the galaxy have long been lacking.
The team analyzed more than 30,000 molecular clouds in 3D, using carbon monoxide (CO) spectral-line survey data from the PMO's 13.7-meter millimeter-wave telescope, said Sun Yan, associate researcher at PMO and the paper's first and co-corresponding author.
CO is a key tracer of cold molecular gas, the raw material for star formation. The sample covers about half of the Milky Way's outer disk, reaching up to roughly 26 kiloparsecs from the Galactic center.
Based on these samples, the team constructed the first global warp model of the molecular gas outer disk. After subtracting the large-scale warp background, they detected clear, wave-like vertical undulations, or corrugations, in the residual structure.
"These corrugations appear as large-scale vertical deviations of the disk, likely originating from bending waves excited by external gravitational perturbations," Sun said.
"They may well be the 'ripples' propagating through the outer disk as a result of gravitational disturbances caused by satellite galaxies, such as dwarf galaxies, flying past the Milky Way," Sun added. ■
