The self-calibration method, a new interferometric technique using measurements in the K′-band (2.1 μm) at the CHARA Array, has been used to derive orbits for several spectroscopic binaries. This method uses the wide component of a hierarchical triple system to calibrate visibility measurements of the triple’s close binary system through quasi-simultaneous observations of the separated fringe packets of both. Prior to the onset of this project, the reduction of separated fringe packet data had never included the goal of deriving visibilities for both fringe packets, so new data reduction software has been written. Visibilities obtained with separated fringe packet data for the target close binary are run through both Monte Carlo simulations and grid search programs in order to determine the best-fit orbital elements of the close binary. Several targets, with spectral types ranging from O to G and luminosity classesfrom III to V, have been observed in this fashion, and orbits have been derived for the close binaries of eight targets (V819 Her B, Kappa Peg B, Eta Vir A, Eta Ori Aab, 55 UMa A, 13 Ceti A, CHARA 96 Ab, HD 129132 Aa). The derivation of an orbit has allowed for the calculation of the masses of the components in these systems. The magnitude differences between the components can also be derived, provided that the components of the close binary have a magnitude difference of Delta K < 2.5 (CHARA’s limit). Derivation of the orbit also allows for the calculation of the mutual inclination (Phi), which is the angle between the planes of the wide and close orbits. According to data from the Multiple Star Catalog, there are 34 triple systems other than the 8 studied here for which the wide and close systems both have visual orbits. Early formation scenarios for multiple systems predict coplanarity (Phi < 15 degrees), but only 6 of these 42 systems are possibly coplanar. This tendency against coplanarity may suggest that the capture method of multiple system formation is more important than previously believed.

This thesis deals with the study of the eclipsing binaries with inclination changes, caused by orbital precession due to third body in the system. Methods of semiauthomatic detection of the inclination changing eclipsing binaries among huge lightcurves databases have been developed. These methods have been applied to the ASAS-3 and OGLE III LMC databases. As a result, 39 new systems suspected of orbital precession have been found and 33 of them are situated in the Large Magellanic Cloud, with only one previously studied system. Increasing the number of known multiple systems especially those located outside Milky Way allows to study inter-galactic differences in star formation. In this work, we bring detailed study of ten new systems and restrictions on the third body parameters are presented. Powered by TCPDF (www.tcpdf.org)

Context: Binaries and multiple systems are very frequent and form large fraction of all stellar systems. In contrast to their single counterparts, studying binaries provides the possibility to accurately determine fundamental properties of their components that are needed for testing models of stellar structure and evolution. On top of that, binaries can be used for accurate distance determinations. The mass exchange in close binaries remains the only mechanism, which completely alters their evolution. Aims: The primary goal of my doctoral study was to determine orbital elements of selected systems and properties of their components - masses, radii, and ef- fective temperatures. - In case of more complicated objects (e.g. interacting multiple systems, mass-transferring binaries, . . . ) the secondary goal was to confront our results with predictions of theoretical models. Methods: Studies that I co-authored were based on three different types of ob- servations, each sensitive to partly different properties of studied systems - photometry, spectroscopy, and spectro-interferometry. The analysis was carried out through several "observation-specific" models, whose outcome was critically compared to each other and to previous studies of the object in question. Results: Throughout my study I contributed to: (i)...