Close binary systems (CBS) are gravitationally bound pairs of stars in which the distance between the components is comparable to their radii, dramatically affecting their properties and evolution. In CBS, we can often observe the mutual eclipses of stars, and this allows for accurate measurements of component radii and masses, as well as the distance of the system. These quantities are extremely important because they inform the theories of stellar structure and evolution, and the establishment of the cosmic distance scale.
Within the CBS research group, we investigate specific objects and conduct statistical studies of large samples of objects. The studies of individual CBS are mainly based on photometric measurements from the Kepler and TESS space telescopes and spectroscopic measurements from ground-based observatories. To these data we apply detailed numerical models of various physical processes present in TDS, such as the tidal deformation of stars, mutual irradiation, magnetic activity, mass transfer, the formation of an accretion disk and a common envelope, etc.
In statistical studies, we use both traditional and innovative methods based on machine learning. As the results of these studies, we determine the typical values and distributions of fundamental stellar parameters, which can be used in other areas of astrophysics, e.g. in population synthesis. An example of our work is the digital catalogue of contact binaries of W Ursae Majoris type, which is available at wumacat.aob.rs.