The instrument, called 4MOST (Multi-Object Spectroscopic Telescope), does not take ordinary images of the night sky. Instead, it collects spectra or colours, i.e. the light from stars and galaxies broken down into its wavelengths. By analysing the rainbow-like pattern, researchers can reveal what these stars and galaxies are made of and how fast they are moving through space.
Using 2,438 optical fibres, each as thin as a strand of hair, the instrument can simultaneously observe the light from 2,400 stars in a total of up to 18,000 colour shades. 4MOST is the instrument in the world with the most fibres in combination with spectral resolution, i.e. how fine details can be observed in a star spectrum.
'Every night for five years, 4MOST will collect star and galaxy spectra and ultimately observe tens of millions of stars in our galaxy, the Milky Way. The result will be the most detailed picture to date of the Milky Way’s structure and chemical evolution,' says Thomas Bensby, astronomy researcher at Lund University.
During its first observation, 4MOST was directed at an area that included several spectacular objects. In a single exposure, NGC 253, the so-called Sculptor Galaxy, was observed – a spiral galaxy just over eleven million light-years away that still has intense star formation. Another object was NGC 288, a globular star cluster with around 100,000 very old stars on the outskirts of the Milky Way. In addition, spectra were collected for over 2,000 other objects – from nearby stars to galaxies ten billion light years away.
'During my early years as an astronomer, I observed and analysed stars one by one. This is an astonishing development that requires careful planning and new analysis methods due to the large amount of data produced every night,' says Thomas Bensby.
Behind 4MOST is an international consortium of 30 universities and research institutes in Europe and Australia, led by The Leibniz Institute for Astrophysics Potsdam. Thanks to a project grant from the Knut and Alice Wallenberg Foundation in 2013, Lund University and Uppsala University have been involved from the outset. Both universities have participated in the construction of the instrument's high-resolution spectrograph, which makes it possible to measure the chemical fingerprints of stars with exceptional precision.
'It feels significant that the work is now underway, as astronomers in Lund have leading roles in several of the projects and working groups that have worked and are still working with 4MOST,' says Thomas Bensby.
By 2030, 4MOST will have mapped millions of celestial bodies across the entire southern sky. By analysing their temperatures, movements and chemical composition, researchers hope to answer questions such as: How were the first stars formed? How did the Milky Way evolve? What do dark matter and dark energy consist of?
'Understanding the Milky Way and its star populations is one of the most important pieces of the puzzle in our quest to understand how large spiral galaxies in general are formed and shaped in the universe,' says Thomas Bensby.
Thomas Bensby's profile in the Lund University research portal.