Interferometric Survey of Stellar Parameters: Mass of the metallic A-type binary β Aur
Year: 2026
Type: article
Abstract: Context. Long-baseline optical interferometry provides spatially resolved observations of close binaries, complementing spectroscopic and photometric constraints on stellar parameters. Aims. With the capabilities of the new visible CHARA/SPICA instrument and the multiple spectral band operation of CHARA, our goal is to resolve orbits of short-period binaries and develop a robust framework for combining interferometric, spectroscopic, and photometric observations into a single consistent model. Methods. For our target sample, we selected suitable binaries based on brightness, angular separation, and orbital properties based on the expected performance of the CHARA/SPICA instrument. As a case study, we analysed the bright eclipsing binary β Aurigae, composed of two slightly evolved A1 stars. We combined new interferometric observations of β Aur obtained with CHARA/SPICA, MIRC–X, and MYSTIC with archival MIRC data, radial velocities, and light curves. We first derived astrometric positions from interferometric observables and computed an orbital solution. Afterwards, we implemented a unified model, capable of tying interferometric modelling with the ellc code to simultaneously fit all observables using MCMC sampling. We performed a detailed analysis of the noise statistics of each data set and in the end we adopted a profile likelihood approach to account for underestimated noise and systematics. Results. We derived a consistent orbital and physical solution for β Aur through joint modelling. The inclusion of interferometric data tightly constrains the angular semi-major axis and inclination. Using profile likelihood to account for the different intrinsic levels of uncertainty of the fundamentally different observables, we derived the masses of the two stars, M 1 = 2.359 ± 0.005 M ⊙ and M 2 = 2.293 ± 0.004 M ⊙ , their radii R 1 = 2.752 ± 0.002 R ⊙ and R 2 = 2.622 ± 0.002 R ⊙ , and the distance to the binary, d = 24.30 ± 0.05 pc.
Source: Astronomy and Astrophysics
Authors: J. Jonák, D. Mourard, J. D. Monnier, S. Hoin, M. Brož, A. Oplištilová, K. A. Kubiak, N. Ebrahimkutty, R. V. Ibañez-Bustos, H. Nowacki, M. Vrard, M. Bailleul, P. Bério, J. Dejonghe, R. Ligi, F. Morand, N. Nardetto, D. Salabert, S. Deheuvels, A. Domiciano de Souza, A. Meilland, K. Perraut, M. Wittkowski, S. Kraus, N. Anugu, M. Gutierrez
Institutions: Centre National de la Recherche Scientifique, Université Côte d'Azur, Observatoire de la Côte d’Azur, University of Michigan, Charles University, University of Liège, Georgia State University, Mount Wilson Observatory, Université Toulouse III - Paul Sabatier, Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Institut de Planétologie et d'Astrophysique de Grenoble, Université Grenoble Alpes, European Southern Observatory, European Southern Observatory, University of Exeter
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
OpenAlex ID: W7171975571