Visual binary Visual binary A visual binary is a gravitationally bound system that can be resolved into two stars. These stars are estimated, via Kepler's 3rd law, to have periods ranging from a number of years to thousands of years. A visual binary consists of two stars, usually of a different brightness. Because of this, the brighter star is called the primary and the fainter one is called the companion. If the primary is too bright, relative to the companion, this can cause a glare making it difficult to resolve the two components. However, it is possible to resolve the system if
Kepler object of interest planet that is substantially larger than what is estimated by "Kepler". This occurs when there are sources of light other than simply the star being transited, such as in a binary system. In cases such as these, there is more surface area producing light than is assumed, so a given transit signal is larger than assumed. Since roughly 34% of stellar systems are binaries, up to 34% of KOI signals could be from planets within binary systems and, consequently, be larger than estimated (assuming planets are as likely to form in binary systems as they are in single star systems).