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Lookup NU author(s): Dr Dominic BowmanORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Beta Cep stars in eclipsing binary (EB) systems give us an opportunity to put observational constraints on their structure and stellar parameters. We present a comprehensive analysis of the beta Cep star in the EB V446 Cep using TESS photometry and HERMES spectra. We calculate the stellar and orbital parameters using light curve modelling and spectral disentangling. The EB has an orbital period of 3.808567 ± 0.000012 d and a mass ratio of 0.1550 ± 0.0012. We find the beta Cep star to have a mass of 10.68 ± 0.06 solar masses, a radius of 5.864 ± 0.033 solar radii, and an effective temperature of 24220 ± 180 K. The secondary has a mass of 1.657 ± 0.017 solar masses, a radius of 1.530 ± 0.014 solar radii, and an effective temperature of 9080 ± 390 K. We also extract the abundances of C, N, O, Mg, and Si for the Beta Cep star, which are found to be consistent with galactic OB binaries. We identified 21 distinct pulsation frequencies, with the dominant mode at 10.24324 c/d, which corresponds to a near-harmonic of the system's orbital frequency. The two stars in the EB have asynchronous rotation, with both stars rotating faster than the orbital frequency. We detect a companion to the EB using eclipse timing variations and period changes of the dominant pulsation frequency. We calculate the minimum mass of this tertiary companion to be 4.11 ± 0.32 solar masses which is on an orbit of 2303 ± 69 d around the EB. Using spectral energy distributions and MIST isochrones, we conclude that V446 Cep is either a co-evolving hierarchical 2+2 quadruple or a triple system where the third body is a compact object.
Author(s): Moharana A, Southworth J, Pavlovski K, Miszuda A, Rathour RS, Helminiak KG, Marcadon F, Bowman DM, Pawar TB, Tkachenko A
Publication type: Article
Publication status: Published
Journal: Monthly Notices of the Royal Astronomical Society
Year: 2026
Volume: 548
Issue: 4
Print publication date: 01/06/2026
Online publication date: 23/04/2026
Acceptance date: 17/04/2026
Date deposited: 19/06/2026
ISSN (print): 0035-8711
ISSN (electronic): 1365-2966
Publisher: Oxford University Press
URL: https://doi.org/10.1093/mnras/stag772
DOI: 10.1093/mnras/stag772
Data Access Statement: The TESS data used in this article are available in the MAST data archive (https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html). The HERMES spectra used in the article are available at: https://doi.org/10.5281/zenodo.17513474. The ETV measurements are available in the online Supporting Information corresponding to the article.
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