Hi there. My name's Dimitri. I got a 10 inch Dobsonian half a year ago and been enjoying the night skies ever since. A few days ago I gazed at the double cluster's h Persei (NGC 869) and noticed a particular feature. There are 5 blue stars around a super giant V520 in a form of a "paw". However, one of the stars was flickering, completely disapearing for 5-6 seconds and appearing again in the view. All other neighbor stars were completely still. I have checked that star out two nights after and saw an exactly identical dimming-brightening pattern. What could be a logical explanation for this? Thanks!