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Synchronous Rotation In The Eclipsing Binary 68 Herculis Inferred From Doppler Shifts In Its Spectrum And Light Curve Modeling, Kenneth W. Mclaughlin, Janak Panthi

Journal of the Iowa Academy of Science: JIAS

Our differential photometry of the eclipsing binary 68 Herculis through V- and R-filters shows periodic minima consistent with a previously established period. As a function of its orbital motion, we report spectra over a limited wavelength range encompassing H-alpha 656.3 nm and helium 667.8 nm lines. Doppler shifts of both stars were resolved in H-alpha, while only the more massive star rendered the helium line with Doppler shifts that agree with the radial velocity we derive for it from the H-alpha profile. Sinusoidal curve-fits to the orbital dependence of the radial velocities imply circular orbits for both components, with amplitudes …