Chromospheric activity in several single late-type stars

New high-resolution echelle spectra of six single late-type Pleiades-like stars (V368 Cep, EP Eri, DX Leo, GJ 211, PW And and V383 Lac) were obtained with the 2.16 meter telescope at Xinglong Station in 2008–2010. Using the spectral subtraction technique, we analyzed our spectroscopic data and calculated the equivalent widths of excess emission from several indicators of chromospheric activity (Na I D₁, D₂, Hα and Ca II infrared triplet lines). All our results using chromospheric activity indicators confirmed the previous findings. In addition, the maximum amplitudes of chromospheric rotational modulation and the ratio of EW₈₅₄₂/EW₈₄₉₈ were found to rise with increasing v sin i velocity. (research papers)