INVESTIGADORES
SAFFE Carlos
congresos y reuniones científicas
Título:
Elemental Abundances in CP Stars of Galactic Open Clusters
Autor/es:
SAFFE, CARLOS; LEVATO, HUGO; LÓPEZ-GARCÍA, ZULEMA
Lugar:
Córdoba, Argentina
Reunión:
Congreso; X Reunión Regional Latinoamericana de Astronomía; 2001
Institución organizadora:
IAU y Observatorio Astronomico Cordoba
Resumen:
Abstract. The diffusion theory predicts the anomalous abundances seen in CP stars. Some ions sink in a stable atmosphere and other are pushed up. This process is time dependent. Should Silicon CP stars present an abundance pattern that depends on age?. We are trying to answer this question measuring abundances of CP stars belonging to open clusters with a span of ages. We have selected from Mermilliod's data base of open clusters, some Silicon stars among members of southern open clusters: NGC 3114 (log age = 8.09) Num. 24 (Teff = 10500 K, log g = 2.6:), Num. 25 (Teff= 12530 K, log g = 3.26) and Num. 108 (Teff = 12500 K, log g = 3.25); NGC 3532 (log age = 8.49) Num. 449 (Teff = 12540 K, log g = 3.87) and NGC 6087 (log age = 7.97) Num. 5 (Teff = 12600 K, log g = 4.02). The spectroscopic observations were performed with a REOSC echelle spectrograph attached to Jorge Sahade 2.1 meter telescope at Complejo Astronomico El Leoncito, San Juan, Argentina. The detector is a 1024 X 1024 TEK and the 2-pix resolution is 0.28 uA . The spectra were reduced with IRAF using standard procedures. The effective temperatures and log g were determined using the Geneva photometry and, with these values, we chose the model atmosphere from Kurucz's models (private communications). We have used the code SPECTRUM and a routine called Blackwell to derive abundances starting from the equivalent widths of the lines measured. The code permits to derive abundances and microturbulent velocities simultaneously using Blackwell diagrams. We have checked the results with those obtained using the standard Kurucz's WIDTH code and we have obtained a perfect agreement. As this is an ongoing program, once more data become available for the whole range of cluster's ages, we will be able to discuss the statistical relation between the abundances of relevant atomic elements with age.