RS Canum Venaticorum variable

The variable type consists of close binary stars[1] having active chromospheres which can cause large stellar spots.

Otto Struve (1946) first called attention to the group, but it was Oliver (1974) who was the first to formally propose a set of observational characteristics to define the RS CVn criteria.

Eaton and Hall (1979) determined that the simplest mechanism for the creation of the distortion wave was "starspots", which, in analogy to sunspots, are large, cool active regions on the photosphere.

Chromospheric activity is signaled by the presence of emission cores in the Ca II H and K resonance lines.

Another subgroup of RS CVns is known to have infrared excess emission, seen by the Spitzer Space Telescope[5]