Spectroscopic and Photometric Study of the Eclipsing Binary Star sigma Aquilae

Abstract

We report on spectroscopic and photometric observations of the eclipsing binary star sigma Aquilae (44 Aql). Archival TESS and Hipparcos data are used to confirm the orbital period of 1.95028 ± 0.00002 days, consistent with previous measurements. Doppler shifts of the He I line at 4922 Angstroms from high-resolution spectroscopic data were used to model the system's orbital motion. From this we were able to determine a mass ratio of the two stars of M₂ / M₁ = 0.79, an inclination angle of the orbital plane of i = 72 degrees, masses of M₁ = 5.8 M_⊙ and M₂ = 4.6 M_⊙, and radii of 3.7 and 3.3 solar radii, respectively. The mass ratio is consistent with previous results, but we note that our derived masses are lower by approximately 5-10% with respect to most of the previous studies.