Identification of Variable Red Dwarf Stars in the ASAS Catalog

Many stars classified as miscellaneous by an analysis program for the All Sky Automated Survey (ASAS) have actually been misidentified, including red dwarfs known as BY Draconis-type variables. These stars exhibit an irregular periodicity, as well as changes in their mean brightness and amplitude. These irregularities can be attributed to chromospheric activity or spots rotating with the surface of the star. From a list of approximately 1600 “miscellaneous” ASAS stars, possible BY Dra stars, and other well-known types, were identified.  This identification is done by analyzing the light curve in the analysis program VStar, made by the AAVSO (American Association of Variable Star Observers), which uses data from the ASAS website to plot a light curve and search for candidate periods. Many of VStar's periodic fits are better than those provided by ASAS, and can be used to reclassify these stars. Since red dwarf stars comprise 90% of the stars in our galaxy they are increasingly the target for exoplanet searches, and the impact of spots and chromospheric behavior on the light curves can complicate such searches. Correcting the classification of red dwarf stars in the AAVSO Variable Star Catalog (VSX) is therefore an important step in understanding red dwarf stars.