Variable Yellow and Red Stragglers in the Old Open Cluster NGC 6791

Two sets of archive time series observations of an old open cluster NGC 6791 were reanalyzed using an image subtraction technique. We report identification of four new variable stars. Proper motion data are available for three of them and indicate that they are likely cluster members. Photometry of these stars is discussed along with the data for two earlier identified variables. The sample analyzed includes one yellow and three red stragglers. An eclipsing red straggler V9 is of particular interest. Cluster membership of this RS Cvn type binary would imply that its cooler component is in a stage of thermal inequilibrium. One of variables is a K type red giant showing low-amplitude variability with a period of about 0.33 d.