103 research outputs found
Turbulent mixing of r-process elements in the Milky Way
We study turbulent gas diffusion affects on -process abundances in Milky
Way stars, by a combination of an analytical approach and a Monte Carlo
simulation. Higher -process event rates and faster diffusion, lead to more
efficient mixing corresponding to a reduced scatter of -process abundances
and causing -process enriched stars to start appearing at lower
metallicities. We use three independent observations to constrain the model
parameters: (i) the scatter of radioactively stable -process element
abundances, (ii) the largest -process enrichment values observed in any
solar neighborhood stars and (iii) the isotope abundance ratios of different
radioactive -process elements (Pu/U and
Cm/U) at the early solar system as compared to their formation.
Our results indicate that the Galactic -process rate and the diffusion
coefficient are respectively r0.1 \mbox{
kpc}^2\mbox{Gyr}^{-1} (r0.5 \mbox{
kpc}^2\mbox{Gyr}^{-1} for collapsars or similarly prolific -process
sources) with allowed values satisfying an approximate anti-correlation such
that , implying that the time between two -process events
that enrich the same location in the Galaxy, is \tau_{\rm mix}\approx
100-200\mbox{ Myr}. This suggests that a fraction of ()
of the observed Cm (Pu) abundance is dominated by one
-process event in the early solar system. Radioactively stable element
abundances are dominated by contributions from different events in
the early solar system. For metal poor stars (with [Fe/H]), their
-process abundances are dominated by either a single or several events,
depending on the star formation history.Comment: 11 pages, 9 figures, accepted for publication in MNRA
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