This method involves the study of deviations from the regularity of a periodic astronomical phenomenon. In this case, the phenomenon is a change of brightness of a binary system as a result of mutual components eclipses during their orbital motion. If there is any additional object in the system (e.g. planet), it causes a shift of the center of mass of the entire binary system, resulting in a periodic variation of the distance from the observer to a binary system with a period equal to the period of the third body in a system. As a result, due to the finite speed of light, brightness changes of a binary system reach the observer with a given irregularity. The main goal of the project is a detection of such irregularities. The abovementioned method was already used in the XVII century by Ole Rømer to estimate the speed of light by measuring the time of eclipses of Jovian satellites. Current approach allows for much greater precision and requires building a network of photometric telescopes, which can carry out continuous observations of selected binary systems.

With a global network of four robotic telescopes it is possible to search for extrasolar planets around binary stars, as well as characterize such stellar systems. Analysis of carefully planned photometric and spectroscopic observations of selected binary systems enables to determine basic stellar parameters, such as mass and radius, with unprecedented precision. In order to get accurate characteristic of binary systems components, apart from high-precision photometry, spectroscopic observations employing high-resolution spectrographs are required.

Spectroscopic Survey

In 2008 we started regular spectroscopic observations of detached eclipsing binary systems selected from the ASAS ACVS catalogue. This part of the work is currently led by dr Krzysztof Hełminiak. Initially with a limited access to the telescopes AAT (3.9-m) with UCLES spectrograph in Australia and Radcliffe (1.9-m) with the GIRAFFE spectrograph in South Africa, and since the end of 2010 much more intensively, mainly using the telescopes located in Chile: CTIO – 1.5m/CHIRON, MPG – 2.2m/FEROS, Euler – 1.2m/CORALIE, and ESO – 3.6m/HARPS. Additional observations are carried out in the northern hemisphere employing instruments located on the Canary Islands: TNG/HARPS-N (3.5 m) and NOT/FIES (2.2 m), France: OHP-1.9m/SOPHIE, and in Hawaii: Subaru/HDS (8.2 m). The program is called Comprehensive Research with Echelles on the Most interesting Eclipsing binaries (CREME). In 2014 we expanded the observing program on the northern hemisphere systems, beyond the ASAS targets, selected from other sources like Super-WASP, NSVS, and Kepler catalogues. These observations are conducted mainly using Japanese OAO-1.88m telescope spectrograph HIDES. We also started monitoring of selected targets in infrared using spectrograph IRCS on the Subaru telescope.

The number of observed objects reaches few hundreds, and collected spectra – thousands. We use every spectrum to calculate radial velocities required to determine the masses and other parameters of studied stars. Thanks to such approach we can determine what type of system we deal with and discover many interesting objects. In our sample one can find low mass and high mass stars, evolved giants, young objects before the main sequence, as well as multiple systems.