Precise physical parameters of three late-type eclipsing binary giant stars in the Large Magellanic Cloud

¹ Nicolaus Copernicus Astronomical Centre, Bartycka 18, 00-716 Warsaw, Poland
² Nicolaus Copernicus Astronomical Centre, Rabiańska 8, 87-100 Toruń, Poland
³ Departamento de Astronomía, Universidad de Concepción, Casilla 160-C, Concepción, Chile
⁴ Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101-1292, USA
⁵ Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warsaw, Poland
⁶ Department of Physics and Astronomy, Uppsala University, Box 516 SE-751 20 Uppsala, Sweden
⁷ Leiden Observatory, Leiden University, P.O. Box 9513 2300 RA Leiden, The Netherlands

^⋆ Corresponding author; rojas@camk.edu.pl

Received: 30 July 2024
Accepted: 21 October 2024

Abstract

Context. Detached eclipsing binaries (DEBs) allow for the possibility of a precise characterization of their stellar components. They offer a unique opportunity for deriving their physical parameters nearly independent of a model for a number of systems consisting of late-type giant stars. We aim to expand the sample of low-metallicity late-type giant stars with precisely determined parameters.

Aims. We determine the fundamental parameters, such as the mass and radius, or the effective temperature for three long-period late-type eclipsing binaries from the Large Magellanic Cloud: OGLE-LMC-ECL-25304, OGLE-LMC-ECL-28283, and OGLE-IV LMC554.19.81. Subsequently, we determine the evolutionary stages of the systems.

Methods. We fit the light curves from the OGLE project and radial velocity curves from high-resolution spectrographs using the Wilson-Devinney code. The spectral analysis was performed with the GSSP code and resulted in the determination of atmospheric parameters such as effective temperatures and metallicities. We used the isochrones provided by the MIST models based on the MESA code to derive the evolutionary status of the stars.

Results. We present the first analysis of three DEBs composed of similar helium-burning late-type stars that pass through the blue loop. The estimated masses for OGLE-LMC-ECL-29293 (G4III + G4III) are M₁ = 2.898 ± 0.031 and M₂ = 3.153 ± 0.038 M_⊙, and the stellar radii are R₁ = 19.43 ± 0.31 and R₂ = 19.30 ± 0.31 R_⊙. OGLE-LMC-ECL-25304 (G4III + G5III) has stellar masses of M₁ = 3.267 ± 0.028 and M₂ = 3.229 ± 0.029 M_⊙ and radii of R₁ = 23.62 ± 0.42 and R₂ = 25.10 ± 0.43 R_⊙. OGLE-IV LMC554.19.81 (G2III + G2III) has masses of M₁ = 3.165 ± 0.020 and M₂ = 3.184 ± 0.020 M_⊙ and radii of R₁ = 18.86 ± 0.26 and R₂ = 19.64 ± 0.26 R_⊙. All masses were determined with a precision better than 2% and the precision for the radii is better than 1.5%. The ages of the stars are in the range of 270–341 Myr.