The Influence of Binarity on Stellar Activity

It is well-known from surveys of various activity signatures on high number of active stars that those stars which are members of close binaries show higher degree of magnetic activity than single stars of similar types and with similar rotational rates. The first models of common magnetic fields of close binaries were constructed as early as in the mid-1980's, but not much theoretical work followed until the early 2000's. In this talk I briefly summarize the recent knowledge of the activity of stars in close binary systems. The emergence of flux tubes from the deeper layers of the active star, which are thought to be the sources of the observed activity, is affected by the tidal effects that breaks the rotational symmetry. Examples will be shown on stellar active longitudes with respect of the companion stars, at the quadratures and substellar points. The corotation latitudes and preferred spot latitudes will be compared as the observations and models reveal.