II Pegasi is an RS CVn binary star system consisting of a main-sequence star and a K2IV subgiant which are tidally locked and orbit one another with a 6.724333-day period. The subgiant is known to exhibit large dark starspots on its surface. Like sunspots, starspots are thought to represent regions of strong magnetic field which suppress convection within the plasma in which they are embedded. The inhibition of convection substantially reduces the transport of energy into a spot from deeper layers, causing it to be cooler and thus darker than the surrounding stellar surface. The brightness of the star varies as the star’s rotation carries the spots into and out of view of Earth. In this study B- and V- filter light curves obtained from 1987–2007 via the Vanderbilt/Tennessee State 0.4-m Automated Photometric Telescope were inverted to produce images of the starspots in order to look for evidence of latitude-dependent differential rotation on the spotted star’s surface. This is of interest because differential rotation is an essential ingredient in stellar magnetic dynamo models. The surface maps presented here exhibit evolution of the starspots over time and provide convincing evidence that the star’s equatorial regions rotate faster than higher latitudes, as is observed on the Sun.

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