Search And Study Of Eclipsing Binaries

Eclipsing binaries pla.y an important role in the invest.igation of the funda-mental stellar parameters,stellar evolution and stellar structure theories.At the same time,eclipsing binaries can help us resolve some astrophysical problems,such as O,Connell effect(O'Connell,1951)and Algol paradox(Pustylnik,2005).Light curves of binary systems can provide valuable information on the bright-ness ratio,orbital inclination,relative stellar sizes,mass ratio,eccentricity,etc(Andersen,1991).In addition,CCD times of minimum can be used to investigate the evolution and the tertiary companion of binaries.So photometric observation is an indispensable tool for studying and analyzing binaries.In this paper,in order to find candidates of eclipsing binary systems,the two month continuous observation data(r' and i' band)derived from the Xingming Observatory and the nine years mutiband observation data,obtained by the Weihai Observat.ory were analyzed by the C-Munipack software.Then the complete light curves of the targets were obtained using the IRAF software.By analyzing the photometric solutions of the eclipsing binaries:we can search for the eclipsing binaries lying in key evolutionary stages or find unusual binary systems,such as extremely low mass ratio or very short period eclipsing binaries,and investigate O'Connell effect and orbit period variations etc.1.By analysing the data of Xingming Observatory,the main results are obtained as follows:(1)Twenty four eclipsing binaries were found,including six new discoverecdbiinaries.(2)Photometric solutions of twenty four binaries are presented,including nine detached binaries.ten semi-detached binaries and five contact binaries.All the light curves of 5 contact binaries show O'onnell effect.(3)Two detached binaries.N311132364 and GSC 03698-00022 are found to be lying in key evolutionary stages.N311132364 was a detached binary with a.low mass ratio(q=0.117)and a short period(0.25817 days).The secondary star is almost overflowing its inner Roche lobe(the filling degree is about 99%).GSC 03698-00022 is a detached binary with an extremely low mass ratio of q=0.059.The secondary component is nearly overflowing the Roche lobe(the filling degree is about 93%).The total eclipsing light curves imply the derived mass ratio is reliable.(4)Two binaries were identified as Algol-type binary systems with extremely mass ratio lower than 0.10.The new discovered binary NAIT000731 has an extremely low mass ratio of q=0.050,the primary star is nearly overflowing the inner Roche lobe(the filling degree is about 73%).NSVS 1908107 also has an extremely low mass ratio of q=0.06.the filling degree of the primary component is 61%.(5)Two low mass ratio contact binaries are found.Mis V1395 is an A-subtype low mass ratio overcontact binary(q=0.150,f=87%),but NSVS 1917038 is a shallow contact low mass ratio binary(q=1/6.839=0.146,f=5%).Both the binaries are lying in the key stage of evolution.2.By analyzing the nine years observational data of Weihai Observatory,the following results are obtained.(1)Five eclipsing binaries are found(two eclipsing binaries are not ana-lyzed in this paper).including three new discovered binaries.The three analyzed binaries belong to the low mass ratio deep contact binaries(q ?0.25,f? 50%).(2)Eclipsing binaries,UCAC4 662-103422 and GSC 02265-01456 are found to reach the lower mass ratio limit,and have high fillout factors of f=91.5%and f=82.5%,respectively.The binary UCAC4 662-103422 has changed its subtype(between W-subtype and A-subtype in a few days.Moreover,O,Connell effect is changing with the observation time,which indicates that the magnetic activity is strong.An interesting phenomena was found for UCAC4 662-103422:a sudden dimming of the brightness happened in the nine years observation.The authenticity for the decreasing of the brightness was identified by the data observed by UVOT of the Swift satellite(Roming et al.,2005)and the data from VSX(AAVSO).UCAC4 662-103422 and GSC 02265-01456,are the potential candidates for merging,like V1309 Sco,due to the extremely mass ratio and xiv high fillout factors.(3)By observing two contact binaries(V0474 Cam and LP UMa)using 1.0 m telescope,O'Connell effect was found in the two binaries.Considering the eight contact binaries found in data of the Xingming Observatory and Weihai observatory,also have O'Connell effect.The O'Connell effect may be a common phenomenon in the contact binaries,which may be due to the common magnetic activity of the components.