Spectroscopic and Photometric Study of the Eclipsing Binary Star σ Aquilae

Volume 51 number 1 (2023)

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Ulisse Quadri

IAU station 565, Bassano Bresciano Astronomical Observatory, Brescia, Italy; info@ulisse.bs.it

Luca Strabla

IAU station 565, Bassano Bresciano Astronomical Observatory, Brescia, Italy; lucapietro.strabla@fastwebnet.it

Lorenzo Franco

IAU station A81, Balzaretto Observatory, Rome, Italy; lor_franco@libero.it

Abstract

We report on spectroscopic and photometric observations of the eclipsing binary star σ 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.