Y. S. Ting, K. C. Freeman, C. Kobayashi, G. M. De Silva, J. Bland-Hawthorn
[Shortened] In preparation for the HERMES chemical tagging survey of about a
million Galactic FGK stars, we estimate the number of independent dimensions of
the space defined by the stellar chemical element abundances [X/Fe]. [...] We
explore abundances in several environments, including solar neighbourhood
thin/thick disk stars, halo metal-poor stars, globular clusters, open clusters,
the Large Magellanic Cloud and the Fornax dwarf spheroidal galaxy. [...] We
find that, especially at low metallicity, the production of r-process elements
is likely to be associated with the production of alpha-elements. This may
support the core-collapse supernovae as the r-process site. We also verify the
over-abundances of light s-process elements at low metallicity, and find that
the relative contribution decreases at higher metallicity, which suggests that
this lighter elements primary process may be associated with massive stars.
[...] Our analysis reveals two types of core-collapse supernovae: one produces
mainly alpha-elements, the other produces both alpha-elements and Fe-peak
elements with a large enhancement of heavy Fe-peak elements which may be the
contribution from hypernovae. [...] The extra contribution from low mass AGB
stars at high metallicity compensates the dimension loss due to the
homogenization of the core-collapse supernovae ejecta. [...] the number of
independent dimensions of the [X/Fe]+[Fe/H] chemical space in the solar
neighbourhood for HERMES is about 8 to 9. Comparing fainter galaxies and the
solar neighbourhood, we find that the chemical space for fainter galaxies such
as Fornax and the Large Magellanic Cloud has a higher dimensionality. This is
consistent with the slower star formation history of fainter galaxies. [...]
View original:
http://arxiv.org/abs/1112.3207
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