Light-Time Effect in the Early-Type Close Binary ZZ Cassiopeiae

CCD observations of the eclipsing binary ZZ Cas were carried out during three nights from 2007 to 2008. Based on our new CCD times of light minimum and all available photoelectric and CCD data compiled from the literature, orbital period changes of ZZ Cas were analyzed. It was discovered that there may exist two cyclic variations (i.e., P-3 = 13.63 yr and A(3) = 0.02406 d, P-4 = 3.89 yr and A(4) = 0.00295 d). ZZ Cas is composed of early type component stars; the two cyclic variations can be explained by the light-time effect via the presence of the third and fourth bodies in the system. Minimal masses Of M-3 = 5.00 M-circle dot and M-4 = 1.21 M-circle dot were also calculated, respectively. These conclusions are in agreement with the result of previous investigations, that the additional bodies should contribute 23.6% to the total light of the system (Zasche 2009, New Astron., 14, 129), when the inclinations of the third and the fourth bodies are i(3) = i(4) = 58.degrees 9. The third and fourth bodies orbit the eclipsing binary at orbital distances of a(3) = 11.74 AU and a(4) = 6.14 AU, respectively.