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

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 Rømer delay between primary and secondary minima yields a mass ratio of q = 0.299 ± 0.009, enabling robust simultaneous modeling of the light and radial velocity curves with phoebe 2.17. By fixing the albedo of the secondary to its maximum physically plausible value (A2 = 1.0), despite the degeneracy between albedo, surface temperature, and radius, we obtained a satisfactory fit, resulting in a significantly lower temperature (T2 ~ 2360 K) and a radius (R2 ~ 0.16 R⊙) 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 ~13-year orbit in all competing models, while the eccentric (e ~0.46) models perform better in terms of fit statistics.