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Splinter Meeting F: "Chemical Oddballs in the Galaxy"

Source: European Southern Observatory/ESO

Splinter presented at the Annual Meeting of the Astronomische Gesellschaft 2015, Kiel, Germany


Programme   (click on the name of the presentation for the abstract)

Day 1, Tuesday, Sep. 15, 2015: Carbon enhancements and surveys

Day 2, Friday, Sep. 18, 2015: Model predictions and chemical peculiarities

Associated Posters   (click on the name of the presentation for the abstract)

Artist's conception of a young planetary system. Image credit: NASA
Scientific rationale

The astronomical landscape of the coming decades will be dominated by large-scale spectroscopic surveys, such as the Gaia-ESO Survey (2012-2017), 4MOST (>2021), and LAMOST (ongoing) that will map the chemo-dynamics of the Milky Way and reconstruct its formation history by observing tens of millions of stars. On small scales, chemical studies of stars, planets, and meteorites are timely if we want to investigate criteria that affect the presence of life on various objects.

The oldest components of galaxies were witness to the earliest chemical enrichment phases. These comprise halo field stars, globular clusters, and low-mass dwarf galaxies, which, in turn, bear the nucleosynthetic imprints of the 'first stars' in the Universe. Many chemical elements are unique indicators for specific time scales for chemical enrichment and thus the evolutionary histories of stellar systems. Amongst these are alpha- and r-process elements, which trace rapid enrichment via short-lived supernovae of type II, vs. s-process elements that indicate enrichment by Asymptotic Giant Branch stars on longer time-scales. Their abundances accordingly follow well-defined trends.

A critical role for understanding Galactic evolution lies in objects with anomalous chemical abundance patterns, which can be interpreted as resulting from the enrichment from very few, massive stars in the early Universe. Discovering and studying such objects is thus of critical importance for studies of galaxy evolution. They will also provide insight into the nature of those massive Population III stars and can reveal details of the nucleosynthetic processes that created the elements..

We therefore want to investigate such "chemical oddballs" in all major Galactic components (halo, bulge, disks), which we expect to be revealed in large numbers in large spectroscopic surveys, down to smaller scales of meteorites, planets, and stars, where peculiar abundance patterns carry key information on their formation scenarios. The aim of this splinter meeting is thus to combine observations and theory to explore the chemical oddballs and to discuss:

  • How can surveys be efficiently exploited to detect "oddballs"?
  • What makes an object a chemical oddball?
  • Which constraints on the formation of the Milky Way and the nucleosynthesis of the elements can be drawn from these objects?
  • How can theories and observations mutually benefit each other, e.g., in terms of improved chemical yields and stellar atmospheres?
  • How do chemical peculiarities in stars relate to the life-bearing potential of their planets?


If you have any further questions, please do not hesitate to contact any of us:

  • Andreas Koch: akoch [at] lsw [dot] uni-heidelberg [dot] de
  • Camilla Juul Hansen: cjhansen [at] dark-cosmology [dot] dk
  • Norbert Christlieb: nchristlieb [at] lsw [dot] uni-heidelberg [dot] de>
  • Avon Huxor: avon [at] ari [dot] uni-heidelberg [dot] de

Mg/Ca ratio in Milky Way field stars (black). Only a few stars in some low-mass
dwarf galaxies have anomalously high values (red), pointing to a very different
enrichment history of those galaxies.