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arXiv · 2602.09925

A Detailed Study of the Physical and Orbital Characteristics, and Eclipse Timing Variations of the Post Common Envelope Binary DD CrB

Özgür Baştürk·Ezgi Sertkan·Furkan Akar·Ulisse Munari·Barış Güler·Ekrem M. Esmer·Selim O. Selam·Ahmet C. Kutluay·Marek Wolf·Petr Zasche·Hanna Kučáková·Miloslav Zejda·Özlem Şimşir
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Abstract

We present an in-depth analysis of the eclipsing binary DD CrB, composed of a B-type subdwarf primary and an M-type main-sequence secondary, with the main goal of investigating its eclipse timing variations (ETVs). Our new multi-color photometric observations, radial velocity measurements, and precise eclipse timings from TESS allow us to constrain the system parameters. The Romer delay between primary and secondary minima yields a mass ratio of $q = 0.299 \pm 0.009$, enabling robust simultaneous modeling of the light and radial velocity curves with {\sc phoebe} 2.17. By fixing the albedo of the secondary to its maximum physically plausible value (A$_2 = 1.0$), despite the degeneracy between albedo, surface temperature, and radius, we obtained a satisfactory fit, resulting in a significantly lower temperature ($T_2 \sim 2360$ K) and a radius ($R_2 \sim 0.16$ R$_\odot$) in agreement with literature values. Using the total mass of the components and the orbital size derived from this modeling, we interpret the ETVs and find them best explained by a Jupiter-mass tertiary companion on a $\sim13$-year orbit in all competing models, while the eccentric (e $\sim0.46$) models perform better in terms of fit statistics.

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Özgür Baştürk, Ezgi Sertkan, Furkan Akar, Ulisse Munari, Barış Güler, Ekrem M. Esmer, Selim O. Selam, Ahmet C. Kutluay, Marek Wolf, Petr Zasche, Hanna Kučáková, Miloslav Zejda, Özlem Şimşir. 2026-02-10. A Detailed Study of the Physical and Orbital Characteristics, and Eclipse Timing Variations of the Post Common Envelope Binary DD CrB. https://arxiv.org/abs/2602.09925

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