Chemical composition of evolved stars in the young open clusters NGC
  4609 and NGC 5316
  High-resolution spectral analysis is performed for the first time in evolved
stars of two young open clusters: NGC 4609 and NGC 5316, of about 80 and 100
Myr in age, respectively, and turn-off masses above 5 Msun. Stellar evolution
models predict an extra-mixing event in evolved stars, which follows the first
dredge-up and happens later on the red giant branch. However, it is still not
understood how this process affects stars of different masses. In this study,
we determine abundances of the mixing sensitive elements carbon and nitrogen,
carbon isotope 12C/13C ratios, as well as 20 other elements produced by
different nucleosynthetic processes (O, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co,
Ni, Y, Zr, Ba, La, Ce, Pr, Nd, and Eu). We compared our results with the latest
theoretical models of evolutionary mixing processes. We find that the obtained
12C/13C and C/N ratios and [Na/Fe] agree quite well with the model which takes
into account thermohaline- and rotation-induced mixing but within error limits
also agree with the standard first dredge-up model. Comparison of oxygen,
magnesium and other alpha-elements with theoretical models of Galactic chemical
evolution revealed that both clusters follow the thin disk alpha-element
trends. Neutron-capture element abundances in NGC 4609 are apparently
reflecting its birthplace in the thin disk, while NGC 5316 has marginally
higher abundances, which would indicate its birthplace in an environment more
enriched with neutron-capture elements.
