Orbital Period Changes and Their Explanations in Two Algol Binaries: WY Per and RW Leo

TL;DR

This study analyzes long-term orbital period changes in two Algol binaries, WY Per and RW Leo, revealing cyclic variations likely caused by third bodies in eccentric orbits, based on new observations and historical data.

Contribution

It provides a detailed reanalysis of period variations in WY Per and RW Leo, identifying multiple cyclic oscillations and proposing third-body explanations with eccentric orbits.

Findings

WY Per exhibits a 71.5-year cyclic period oscillation.

RW Leo shows two cyclic variations of 77.8 and 39.1 years.

Third bodies with eccentric orbits likely cause the observed period changes.

Abstract

WY Per and RW Leo are two Algol-type binaries. Based on our new CCD observations and the almost century-long historical record of the times of primary eclipse for WY Per and RW Leo, the orbital period changes and their explanations were reanalyzed and rediscussed in detail. It is found that the orbital period of WY Per shows a cyclic oscillation with a period of $P_{3} = 71.5$ yr and a semiamplitude of $A_{3} = 0^{\textrm{d}}.0739$. The period variation can be interpreted by the light-travel time effect (LTTE) via the presence of a third body in an eccentric orbit with an eccentricity of $e_{3} \simeq 0.602$ in the system. For RW Leo, its orbital period shows complex variations. Two cyclic variations (i.e., $P_{3} = 77.8$ yr and $A_{3} = 0^{\textrm{d}}.033$, and $P_{4} = 39.1$ yr and $A_{4} = 0^{\textrm{d}}.022$) are discovered. The cyclic variation of $P_{3} = 77.8$ yr and $A_{3} = 0^{\textrm{d}}.033$ can be attributed to the LTTE via the presence of a third body in an eccentric orbit with an eccentricity of $e_{3} \simeq 0.732$.