Spectral observations of red dwarfs II. New observations of flare stars in the Pleiades cluster region

We studied the spectra of 24 flare stars of the Pleiades cluster region obtained on the 2.6m telescope of the Byurakan observatory in the years 1986–1989. From the spectral indices of titanium oxide (TiO) and other chemical elements of the stars investigated we determined their spectral classes and luminosities (absolute visual stellar magnitudes). The agreement of these moduli of the stars with the distance modulus of the Pleiades cluster confirms that 21 of them belong to the cluster. Only three of them (FSP 169, FSP 377, and FSP 435) are possibly not members of the cluster. This indicates that the flare activity of a star is a reliable criterion for its membership in a nearby stellar system (cluster or association).Translated fromAstrofizika, Vol. 37, No. 4, 1994.