Department of Physics and Astronomy

The Milky Way

For obvious reasons, the Milky Way, i.e. the Galaxy itself and its satellites, is the galaxy that can be studied in the greatest detail. Researchers at our division are actively involved in large on-going efforts to take Galactic research to the next level. The primary example of this is ESA's Galactic surveyor mission Gaia (, which since mid-2014 collects data on more than 1 billion stars in the Galaxy. By 2022, we will have a dynamical all-sky map of a significant fraction of the Galaxy, well beyond the Solar neighbourhood. This data set alone will allow us to comprehensively address questions related to the origin and evolution of the Galaxy, as an example for the origin and evolution of galaxies in general. In the Gaia Data Processing and Analysis Consortium (comprising 400 researchers around Europe), we co-lead work packages related to synthetic stellar observables and calibrations.

Gaia has state-of-the-art instrumentation to measure positions, motions and photometric properties of all objects down to V~21. However, it is less well equipped when it comes to spectroscopy, the tool of choice when it comes to detailed stellar properties like elemental composition. Here, ground-based instrumentation can make a significant contribution. Astrophysicists in Uppsala take part in the Gaia-ESO Survey (, a 300-night survey at ESO's Very Large Telescope in Chile. The survey is well under way and observes objects drawn from all major stellar populations of the Galaxy, both in the field and in clusters. The total yield is expected to be detailed information on 100,000 stars. We co-lead work packages on the high-resolution part of the survey and calibrations.

Studying the fossil record of the Milky Way: Galactic archaelogy (artist impression)

We are furthermore involved in two ground-based survey facilities that will complement Gaia with spectroscopic information on even larger numbers of stars: WEAVE ( and 4MOST ( While WEAVE will go on the William-Herschel telescope (La Palma, Spain) as early as 2017, 4MOST will be put on the VISTA telescope at Paranal Observatory (Chile) in 2021. Together, spectra of up to 30 million stars will likely be observed. Uppsala co-leads the work package on the stellar-parameter and chemical-abundance software pipelines.

Our Galactic research is funded by the Swedish National Space Board (SNSB), the Knut and Alice Wallenberg Foundation (KAW), the European Science Foundation (ESF) and the European Commission (EC).

Contacts: Andreas Korn, Karin Lind, Ulrike Heiter