Two groups of researchers have used new observations from high-powered telescopes to create a clearer 3-D map of the Milky Way Galaxy.
Scientists from the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany, used the VVV near-infrared survey from the VISTA telescope at ESO's Paranal Observatory in Chile (eso1101 , eso1128 , eso1141 , eso1242 , eso1309 ).
Astronomers reportedly believe the Galaxy was originally "a pure disc of stars which formed a flat bar billions of years ago," but then "buckled" to form the three-dimensional "peanut shape" in their newest maps, according to a news release.
"The depth of the VISTA star catalogue far exceeds previous work and we can detect the entire population of these stars in all but the most highly obscured regions," explained Christopher Wegg (MPE), who is lead author of the first study, in a news release. "From this star distribution we can then make a three-dimensional map of the galactic bulge.This is the first time that such a map has been made without assuming a model for the bulge's shape."
According to the researchers, the new public survey "can pick up stars thirty times fainter than previous bulge surveys." The scientists were able to identify 22 million stars belonging to a "class of red giants whose well-known properties allow their distances to be calculated."
"We find that the inner region of our Galaxy has the shape of a peanut in its shell from the side, and of a highly elongated bar from above", added Ortwin Gerhard, the coauthor of the first paper and leader of the Dynamics Group at MPE. "It is the first time that we can see this clearly in our own Milky Way, and simulations in our group and by others show that this shape is characteristic of a barred galaxy that started out as a pure disc of stars."
The second team was led by Chilean PhD student Sergio Vásquez (Pontificia Universidad Católica de Chile, Santiago, Chile and ESO, Santiago, Chile). The researchers reportedly compared images taken eleven years apart with the MPG/ESO 2.2-metre telescope.
With the data collected, scientists measured "tiny shifts due to the motions of the bulge stars across the sky," according to the news release. Researchers were able to map out more than 400 stars in three dimensions.
"This is the first time that a large number of velocities in three dimensions for individual stars from both sides of the bulge been obtained," Vásquez said. "The stars we have observed seem to be streaming along the arms of the X-shaped bulge as their orbits take them up and down and out of the plane of the Milky Way. It all fits very well with predictions from state-of-the-art models!"
