Does the Halfa-Ca II relation change over the stellar cycle?

ANDREA BUCCINO; MATÍAS FLORES; MARIELA VIEYTES; PABLO MAUAS

Uppsala, Suecia

Workshop; The 19th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun; 2016

Cambridge and Uppsala universities

Since 1999 the HKα Project 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 5000mid-resolution spectra, ranging from 389 to 669 nm, which constitutean ideal dataset to study long-term activity. As these spectra arecalibrated in flux, they allow us to simultaneously study differentspectral features. Although in the Sun the correlation between the CaII K and Hα line-core fluxes positive, previous works have reportedthat this relation is not always valid for other late stars(F7V-M5V). Each star shows a particular behavior, ranging fromanti-correlations to tight correlations with different slopes,including cases where no correlations are found. Based on our largespectral, we analyzed the relation between simultaneous measurementsof Hα and Ca II H+K fluxes. To discern if this flux-flux relationdepends on the level of activity of the star and if it is associatedwith the distribution of active regions in the stellar atmosphere, welater analyze the relation between Hα-Ca II fluxes for the whole setof solar-type stars and individually for a subset of several ones ofdifferent level of activityp { margin-bottom: 0.25cm; line-height: 120%; }