Image: A collection of objects captured by the VISTA telescope. From left to right and top to bottom: NGC 3576, NGC 6357, Messier 17, NGC 6188, Messier 22 and NGC 3603. (ESO/VVVX survey)
Using the European Southern Observatory’s (ESO) VISTA telescope, the team has observed the central parts of our Milky Way Galaxy for more than thirteen years, collecting five hundred terabytes of data. This makes this the largest observing project ever undertaken with an ESO telescope.
The standard-sized map consists of 200,000 images taken with the Visible and Infrared Survey Telescope for Astronomy (VISTA). This telescope is part of the European Southern Observatory’s Paranal Observatory in Chile, and its main purpose is to map large areas of the sky. Astronomers used the VISTA infrared camera, VIRCAM, which can see through dust and gas in our galaxy. It is therefore able to see radiation from the best hidden spots in the Milky Way, opening a unique window into our galactic environment.
The observations began in 2010 and ended in the first half of 2023. They all took 420 nights. By observing each piece of sky multiple times, the team was able not only to determine the locations of the objects, but also to track their movements and any changes in brightness. This allowed them to map stars whose brightness periodically changes and which could be used as cosmic “yardsticks.” This gave us an accurate 3D image of the central parts of the Milky Way, which until recently were obscured by dust. The researchers also tracked hypervelocity stars: fast-moving stars that were blasted from the center of the Milky Way after a brief encounter with the supermassive black hole lurking there.
