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 The MPA/ESO/MPE/USM 2008 Joint Astronomy Conference

Chemical Evolution of Dwarf Galaxies and Stellar Clusters

NGC1569 (HST)

July 21 - 25, 2008

Garching bei München, Germany


Small stellar systems like dwarf galaxies and globular clusters might be well suited in order to study galactic nucleosynthesis and chemical evolution as to a first approximation they can be treated as simple, homogeneous 1-component objects.

There is intensive work going on in determining stellar abundances in galactic stellar systems (notably globular clusters) and in local-group dwarf galaxies. Many of these projects are actually pursued with the latest instruments, and have revealed surprising results.

Stars in globular clusters on the one hand are characterised be a well-defined iron abundance with a small spread which indicates that they formed from gas that has been pre-enriched. This narrow iron spread is in contrast with the widespread abundance anomalies in light elements which is preferentially explained by "primordial pollution" scenarios. This might imply, at least to some degree, an internal chemical evolution, where presently observed stars formed out of cluster matter polluted by earlier generations of stars, or at least by the more massive objects of the same generation. There are also scenarios which claim that this pollution was due to external field stars in the surrounding of the proto-globular cluster cloud which was part of a small, dwarf-galaxy-like substructure of the Galaxy. This host galaxy was later on disrupted by the Milky Way, while its globular clusters survived and are now part of the MW system.

Dwarf galaxies are likely to have formed, as typical for galaxies, through infall of primordial gas into a dark matter halo. They therefore have their own chemical evolution, which, however, is different from that of large galaxies due to the shallower potential wells, leading to more efficient mixing and a strong influence of galactic tides causing harrassement and tidal disruption. In addition, outflows of enriched hot gas in galactic winds is very likely to affect these systems. Dwarf galaxies are also investigated in integrated light to derive their star-formation history and age-metallicity relations. Some globular clusters are thought to be cores of former dwarf galaxies, in particular those where multiple populations of stars have been found (such as Omega Cen and NGC 2808).

As globular clusters and dwarf galaxies form a mass sequence and as there are the above-mentioned possible connections between the two classes of stellar systems, a confrontation and comparison of cluster and dwarf chemical evolution appears to be interesting and possibly helpful to understand the origin of the abundances in both classes.

Scientific Advisory Committee:

Local Organizing Committee:

Confirmed Review Speakers:
Martin Asplund (MPA, Germany) Francesca Primas (ESO, co-chair) Santi Cassisi (Teramo Observatory, I)
Andi Burkert (USM, Germany) Achim Weiss (MPA, co-chair) Francesca D'Antona (Rome Observatory, I)
Eileen Friel (NSF, USA) Markus Kissler-Patig (ESO) Brad Gibson (Univ. Lancashire, UK)
Mario Mateo (Univ. Michigan, USA) Ewald Müller (MPA) Oleg Gnedin (Univ. Michigan, USA)
Ben Moore (Zurich Univ., Switzerland) Luca Pasquini (ESO) Raffaele Gratton (Univ. Padova, I)
John Norris (Mt. Stromlo, Australia) Bruno Leibundgut (ESO) Eva Grebel (ARI Heidelberg, D)
Francesca Primas (ESO, Germany, co-chair) Maria Depner (MPA) Pavel Kroupa (Univ. Bonn, D)
Achim Weiss (MPA, Germany, co-chair) Sybille Mican (MPA) Mario Mateo (Univ. Michigan, USA)
Rosemarie Wyse (JHU, USA)   Kim Venn (Victoria, CND)