Orbital Period Studies of Two Algol‐Type Eclipsing Binary Systems: TY Pegasi and X Trianguli

Shengbang Qian
2002 Publications of the Astronomical Society of the Pacific  
curves of two EA-type eclipsing binaries, TY Peg and X Tri, are formed and studied in O Ϫ C detail based on all available times of light minimum. For TY Peg, it was discovered that the general trend of the curve showed a downward parabolic variation, which indicates a secular period decrease with rate at O Ϫ C days yr Ϫ1 . When the secular decrease is removed from the curve, the residuals can Ϫ6 dP/dt p Ϫ1.16 # 10 O Ϫ C be described by several linear ephemerides, suggesting several sudden
more » ... everal sudden period jumps. For the other one, X Tri, it is found that the general trend also indicates a secular period decrease ( days yr Ϫ1 ), Ϫ7 O Ϫ C d P /dt p Ϫ1.42 # 10 and several irregular period jumps are found to superpose on the long-time period decrease. This kind of period change, irregular sudden jumps superposed on secular decrease, is typical for many other Algol-type binary systems such as TU Her, UU And, Z Per, Y Psc, BO Mon, FH Ori, RT Per, and TX UMa. The period changes of these systems may be caused by orbital angular momentum loss via variable magnetic coupling and gravity coupling between the components.
doi:10.1086/341681 fatcat:ulqpdm6n4vfrlifwvbajmbs4wu