Indicadores de actividad estelar

CINCUNEGUI, C. C.; MAUAS, P J D

Congreso; reunión Anual de la Asociación Argentina de Astronomía; 1999

Asociación Argentina de Astronomía

There is a strong correlation between some solar activity indexes and average Earth temperature measurements. Thus, determining the range of variation of the solar constant over the years becomes very important. One way to do so, is to consider a large sample of stars with characteristics similar to those of the Sun, and analyze how the activity levels change from one star to another. With this technique one can infer activity variations that may occur over longer periods of time than the ones allowed by direct observations of the Sun. The main index used to measure stellar activity is the flux in the Ca II H and K lines, which are formed in the star's chromosphere. However, these lines are in the blue side of the spectrum, and are, therefore, not useful to study very cool stars, which are intrinsically faint and very red. In this work observations made at CASLEO are presented. Flux calibration of these lines was done in the usual way. We investigate possible correlations between the Ca II line fluxes and those of lines of longer wavelength, which may allow us to study the variability of stars cooler than the Sun.