In the present work we analyze the relationship between rotation and chemical abundance for various s-process elements in a sample of 340 solar-type simple and binary evolved stars along the spectral region from G to K. We present the theoretical basis for the nucleosynthesis, along with the role of stellar evolution, including theoretical predictions obtained from the standard theory. We analyze the relationship between the abundance of s-process elements and the surface temperature of stars in our sample and the relationship between this abundance and metallicity. In addition, we investigate the influence of binarity on such s-element abundances for binary systems with evolved components, using the relationship between abundances and orbital periods. We compare the behavior of s abundances with that of lithium abundances. We note that the abundances in our sample agree, to a good approximation, with those of the universal curve, indicating a high degree of reliability in the data used in this work. In the abundance-temperature relationship, we see that our abundances decrease with temperature, both for simple stars and for binary systems. We also note that synchronized binary systems do not show elevated abundances and that unsynchronized systems show a growing scatter in the values of the abundances. With regard to the rotational behavior, we see that the distribution of abundances follows the same behavior as the rotational velocity, i.e. a gradual decrease with decrease in effective temperature. We note that, both for simple stars and binary systems, all the elements of our sample show an increase in abundance with increasing metallicity. We observe that the abundances of s elements increase with lithium growth. We detect anomalous abundances in some stars, and observe a trend toward a relationship (correlation) between abundance and metallicity in these stars. We note that some stars with enriched abundances show an increase in rotation. We therefore believe that we have succeeded in our objective of analyzing the relationships between diverse stellar and orbital parameters: rotation velocity, s-process abundance, orbital period, metallicity and effective temperature of evolved solar-type stars.
Bulletin of the Astronomical Society of Brazil
- Pub Date:
- August 2003