We present analysis of medium resolution optical spectra and long term V band photometry of four cool stars , \object BD+13 5000 , \object BD+11 3024 , \object TYC 3557-919-1 and \object TYC 5163-1764-1 .
Our spectroscopic analysis reveals that the stars are giant or sub-giant from K0 or K1 spectral type , and all of them exhibit emission features in their Ca ii H & K lines .
These features appear to be modulated with the rotation of the stars .
Except \object BD+11 3024 , we observe that the radial velocities of the target stars are not stable , which suggests that each of them might be a member of a binary system .
Global analysis of photometric data indicates clear cyclic variation for \object BD+13 5000 and \object TYC 5163-1764-1 with a period of 8.0 \pm 0.3 and 5.04 \pm 0.04 year , respectively .
Besides that , we observe a dramatic increase ( \sim 0 \fm 7 ) in the mean brightness of \object BD+11 3024 , accompanied with a 2.87 \pm 0.12 cyclic variation , embedded into the global brightening trend , which indicates possible multiple cycles on this star .