Abstract
We report the discovery of a trend of increasing barium abundance with decreasing age for a large sample of Galactic open clusters. The observed pattern of [Ba/Fe] versus age can be reproduced with a Galactic chemical evolution model only assuming a higher Ba yield from the s-process in low-mass stars than the average one suggested by parameterized models of neutron-capture nucleosynthesis. We show that this is possible in a scenario where the efficiency of the extra-mixing processes producing the neutron source 13C is anticorrelated with the initial mass, with a larger efficiency for lower masses. This is similar to the known trend of extended mixing episodes acting in H-rich layers and might suggest a common physical mechanism.
Original language | English |
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Pages (from-to) | L31-L34 |
Number of pages | 4 |
Journal | Astrophysical Journal |
Volume | 693 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2009 |
Externally published | Yes |