The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here:

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Lego Figure holding a lego telescope. Photo

Arne Ardeberg

Professor emeritus

Lego Figure holding a lego telescope. Photo

Clusters as probes of distance, evolution, and chemistry of galaxies


  • Arne Ardeberg
  • Peter Linde


  • Arne Ardeberg
  • Torben Andersen

Summary, in English

Stellar clusters are highly useful as tools for determination of distances, ages and abundances of heavy elements of galaxies, also at larger distances. Their utility for these purposes has, so far, been severely limited, mainly due to image crowding. The introduction of Extremely Large Telescopes (ELTs) with full adaptive optics (AO) and near diffraction limited performance should imply a drastic improvement concerning the usefulness of clusters and the limiting distances of high quality data. We have made a study of stellar clusters as probes of distance, evolution and chemistry of galaxies at distances from one to twenty Mpc. From data on the Stromgren uvby system, partly from direct measurements taken from the literature, we have synthesized test clusters, one open and one globular, as well as galactic backgrounds. The clusters have been embedded in the backgrounds and located at distances between one and twenty Mpc. Here, vby data have been measured, reduced and analyzed. Color-magnitude diagrams (CMDs), metallicity diagrams (MDs) and luminosity functions (LFs) have been constructed. They have been evaluated absolutely and compared to the corresponding template data. We conclude that with a 50 m AO ELT, for open as well as globular clusters, MDs are of high quality for clusters out to and beyond 5 Mpc and useful out to 10 Mpc. CMDs are of very high quality well beyond 5 Mpc. They are of high scientific value out to and beyond 10 Mpc and valuable for clusters even out to 20 Mpc. LFs are highly informative well beyond 10 Mpc and still rather valuable at 20 Mpc. With sufficient measurement data available, LFs are useful for clusters in galaxies even beyond 20 Mpc


  • Lund Observatory - Has been reorganised

Publishing year







Proceedings of the SPIE - The International Society for Optical Engineering





Document type

Conference paper




  • Astronomy, Astrophysics and Cosmology


  • stellar abundances
  • stellar age
  • stellar clusters
  • clusters evolution
  • galaxy chemistry
  • clusters metallicity diagram
  • CMD
  • cluster luminosity function
  • AO ELT
  • clusters of galaxies
  • 1 to 20 Mpc
  • globular star clusters
  • galactic backgrounds
  • colour-magnitude diagram
  • Extremely Large Telescope
  • ELT
  • adaptive optics
  • open clusters
  • globular clusters

Conference name

Second Bäckaskog Workshop on Extremely Large Telescopes, 2003

Conference date

2003-09-09 - 2003-09-11

Conference place

Bäckaskog Castle, Sweden




  • ISSN: 0277-786X
  • ISSN: 1996-756X