AG Virginis
AG Virginis is an eclipsing binary star system in the equatorial constellation of Virgo. With a maximum apparent visual magnitude of 8.51 it is too faint to be visible to the naked eye. The system is located at a distance of approximately 820 light years from the Sun based on parallax measurements. The variability of this system was first reported by P. Guthnick and R. Prager in 1929. R. S. Dugan determined the periodicity in 1933. C. Blanco and F. Catalano in 1970 proposed that this is a semidetached binary where the primary component has filled its Roche lobe, thereby allowing mass transfer. They noted that the orbital period appeared to vary slightly with a ~40 year cycle, which could be explained by a third component. In 1986, J. Kaluzny produced a model for the light curve which suggested this is instead a contact binary. Multiple observers noted a permanent asymmetry to the light curve, with the primary minimum appearing distorted. A localized "hot spot" hypothesis was proposed to explain this feature. This is a close binary system with an orbital period of . It is classified as a W Ursae Majoris variable, which means the components are in near