Over 1.5 billion objects in the Milky Way have been mapped in a project involving UCL researchers.
Over the course of 13 years, the VISTA Variables in the Vía Láctea (VVV) survey and its extension, the VVV eXtended survey (VVVX), observed the central regions of the Milky Way.
The surveys used VISTA (Visible and Infrared Survey Telescope for Astronomy), a European Southern Observatory (ESO) facility in Chile, with 420 nights of observation capturing approximately 200,000 images, generating 500 terabytes of scientific data.
Notable discoveries include:
- Globular clusters: The oldest objects in our galaxy.
- Hypervelocity stars: Stars expelled from the galaxy by the central supermassive black hole.
- Galactic windows: Clear views through interstellar dust and gas to the other side of the galaxy.
- RR Lyrae variable stars: The oldest known population in the centre of the galaxy.
- Brown dwarf stars and binary floating planets: Unique celestial objects that enhance our understanding of stellar and planetary formation.
Dr Jason Sanders (UCL Physics & Astronomy), who worked on the project, said: "For more than 13 years, the VVVX survey has peered through the dust into the heart of our galaxy watching how the stars are changing. The motions of stars are revealing clues on the formation and evolution of this previously mysterious region and the galaxy as a whole."
Professor Dante Minniti, an astrophysicist at Universidad Andrés Bello in Chile, who led the overall project, said: "We made so many discoveries, we have changed the view of our galaxy forever."
With a 4.1m mirror, VISTA is the world's largest dedicated infrared survey telescope. Its infrared camera VIRCAM can peer through the dust and gas that permeates our galaxy. By observing at wavelengths longer than those visible to the human eye, VISTA has the capability to study objects that would otherwise remain nearly invisible in visible light, such as brown dwarfs ('failed' stars that do not have sustained nuclear fusion) or free-floating planets that don't orbit a star.
A paper marking the completion of observations of the VVV/VVVX surveys has been published in the journal Astronomy & Astrophysics. The article, led by Professor Roberto K. Saito from the Universidade Federal de Santa Catarina in Brazil and Professor Maren Hempel from the Universidad Andrés Bello (UNAB) in Chile, was a collaborative effort involving 146 co-authors from 15 countries and it details numerous discoveries made possible by this extensive dataset.
This data has already produced more than 300 scientific publications and 30 doctoral theses in South America and Europe, covering an incredible range of topics such as galactic structure, stellar populations, variable stars, star clusters and much more.
UCL's Dr Jason Sanders and team, co-authors on the latest study, analysed how fast stars are moving across the sky and what that tells us about the structure of the inner galaxy. They also produced the survey's largest catalogue of variable stars (stars whose brightness changes over time).
The VVV and VVVX surveys were led by Professor Dante Minniti from UNAB and Professor Philip Lucas from the University of Hertfordshire.
Professor Lucas said: "By mapping the Milky Way in the infrared, we were able to pierce the obscuring veil of interstellar dust and gas that hides most of our galaxy in visible light."
The UK's Science and Technology Facilities Council through its team at the UK Astronomy Technology Centre (UK ATC) played a key role in the development and delivery of the VISTA telescope to ESO. Delivery of VISTA was also a major part of the UK becoming a member of ESO.
