Astronomers have unveiled an extraordinary infrared map of the Milky Way, showcasing over 1.5 billion celestial objects—marking the most intricate map ever created. Utilizing the VISTA telescope from the European Southern Observatory (ESO), the research team observed the core regions of our galaxy for over 13 years. With an extensive dataset of 500 terabytes, this initiative stands as the largest observational project conducted with an ESO telescope.
Astronomers have unveiled an extraordinary infrared map of the Milky Way, showcasing over 1.5 billion celestial objects—marking the most intricate map ever created. Utilizing the VISTA telescope from the European Southern Observatory (ESO), the research team observed the core regions of our galaxy for over 13 years. With an extensive dataset of 500 terabytes, this initiative stands as the largest observational project conducted with an ESO telescope.
“We made so many discoveries; our understanding of the Galaxy will never be the same again,” states Dante Minniti, an astrophysicist from Universidad Andrés Bello in Chile, who oversaw the project.
This groundbreaking map is built from 200,000 images captured by the ESO’s VISTA, which stands for the Visible and Infrared Survey Telescope for Astronomy. Set at ESO’s Paranal Observatory in Chile, VISTA’s primary mission is to survey vast regions of the sky. The team employed VISTA’s infrared camera, VIRCAM, which can penetrate the dust and gas clouds that fill our galaxy, enabling it to detect light from the Milky Way’s most obscured areas, thereby providing a unique view of our galactic environment.
This massive dataset [1] encompasses a sky area equivalent to 8600 full moons and features approximately ten times more celestial objects than a previous map released by the same group in 2012. It highlights newly formed stars, often hidden within dense dust clouds, as well as globular clusters—concentrated groups of millions of the Milky Way’s oldest stars. Observing in the infrared spectrum allows VISTA to identify very cold entities, like brown dwarfs (stars that lack sustained nuclear fusion) and free-floating planets that do not orbit a star.
The observation process began in 2010 and concluded in early 2023, accumulating data over a total of 420 nights. By revisiting each section of the sky multiple times, the team could not only pinpoint the locations of these objects but also monitor their movements and brightness variations. They documented stars whose luminosity fluctuates, serving as cosmic benchmarks for distance measurement [2]. This has yielded an accurate 3D representation of the previously obscured inner regions of the Milky Way. The researchers also identified hypervelocity stars—swiftly traveling stars ejected from the galaxy’s center after encountering the supermassive black hole located there.
The newly released map features data collected from the VISTA Variables in the VÃa Láctea (VVV) survey [3] and its associated project, the VVV eXtended (VVVX) survey. “The project required immense effort, made possible by our exceptional team,” comments Roberto Saito, an astrophysicist at the Universidade Federal de Santa Catarina in Brazil and the main author of the paper published today in Astronomy & Astrophysics regarding the project’s completion.
Both the VVV and VVVX surveys have already contributed to over 300 scientific papers. Now that the surveys are concluded, the exploration of the accumulated data will continue for many years. Additionally, preparations are underway at ESO’s Paranal Observatory for future advancements: VISTA will be upgraded with a new instrument, 4MOST, while ESO’s Very Large Telescope (VLT) will enhance its capabilities with the MOONS instrument. Together, these upgrades will provide spectra for millions of objects surveyed, with expectations for countless new discoveries.
Notes
[1] Due to the sheer size of the dataset, it cannot be released as a single image, but processed data and an object catalogue are available through the ESO Science Portal.
[2] One way to determine a star’s distance is by comparing its observed brightness from Earth to its intrinsic brightness; however, the latter is often unknown. Certain star types exhibit periodic changes in brightness, and there is a strong correlation between their variability rate and their intrinsic luminosity. By measuring these brightness variations, astronomers can ascertain the stars’ luminosity and consequently their distances.
[3] VÃa Láctea is the Latin term for the Milky Way.
