Does the Halpha-Ca II relation changes over the stellar cycle?

VIEYTES, M. C.; FLORES, M.; BUCCINO, A. P.; MAUAS. P. J. D.

Conferencia; Cool Stars 19; 2016

Since 1999. the HKα Porject is operating in the Argentinianobservatory CASLEO (Complejo Astronómico El Leoncito). Wesystematically observe more than 150 main-sequence stars from F3 toM5.5 four times a year. To date, we have more than 5000 mid-resolutionspectra, ranging from 389 to 669 nm, which constitute an ideal datasetto study long-term activity.  As these spectra are calibrated in flux, they allow us tosimultaneously study different spectral features. Although in the Sunthe correlation between the Ca ii K and Hα line-core fluxes ispositive, prevoius works have reported that this relation is notalways valid for other late stars (F7V?M5V). Each star shows aparticular behavior, ranging from anti-correlations to tightcorrelations with different slopes, including cases where nocorrelations are found.  Based on our large spectral, we analyzed therelation between simultaneous measurements of Hα and Ca ii H+Kfluxes. To discern if this flux-flux relation depends on the level ofactivity of the star and if it is associated with the distribution ofactive regions in the stellar atmosphere, we later analyze therelation between Hα-Ca ii fluxes for the whole set of solar-type starsand individually for a subset of several ones of different level ofactivity.