Absolute Parameters and Physical Nature of the Low-Amplitude Contact Binary Hi Draconis

Abstract

We present a detailed investigation of the low-amplitude contact binary HI Dra based on the new VR c I c CCD photometric light curves (LCs) combined with published radial velocity (RV) curves. Our completely covered LCs were analyzed using PHOEBE and revealed that HI Dra is an overcontact binary with low fill-out factor f = 24 ± 4 (%) and temperature difference between the components of 330 K. Two spotted models are proposed to explain the LC asymmetry, between which the A subtype of W UMa type eclipsing systems, with a cool spot on the less massive and cooler component, proves to be more plausible on evolutionary grounds. The results and stability of the solutions were explored by heuristic scan and parameter perturbation to provide a consistent and reliable set of parameters and their errors. Our photometric modeling and RV curve solution give the following absolute parameters of the hot and cool components, respectively:Based on these results the initial masses of the progenitors (1.11 ± 0.03  M and 2.25 ± 0.07  M , respectively) and a rough estimate of the age of the system of 2.4 Gyr are discussed.

New low mass ratio contact binaries in the Catalina Sky Survey

“…The temperature uncertainty of the systems is taken from Stassun et al ( 2019 ). The uncertainties in the derived physical parameters are estimated by performing Monte Carlo simulations (Papageorgiou & Christopoulou 2015 ;Papageorgiou et al 2019 ), since the formal errors from the fitting of the LC are heavily underestimated. During this procedure, each photometric point of the observed LC was randomly displaced 1000 times according to its photometric error σ CSS , drawn from a normal distribution with zero mean and σ CSS as standard deviation.…”

Discovery of star systems at the merger limit by large astronomical surveys

“…The photometric properties of the binaries were analyzed by light curve modeling with PHOEBE-0.31a scripter (Prsa & Zwitter, 2005;Papageorgiou et al, 2019), to explore the parameter space through a detailed scan in the mass ratio-inclination plane, using also in some cases the PIKAIA 3 genetic algorithm optimizer. The uncertainties in the derived physical parameters were estimated by performing Monte Carlo simulations (Papageorgiou & Christopoulou, 2015;Papageorgiou et al, 2023). In the absence of spectroscopic data, given the photometric mass ratio of contact binaries with total eclipses, we use our semiempirical mass-luminosity relation for the primary component (Christopoulou et al, 2022) to estimate the absolute parameters log L 1 = log(0.63 ± 0.04) + (4.8 ± 0.2) log M 1 .…”

What we can learn from eclipsing binaries in large surveys: The case of EA Catalina systems

“…We have found 126 candidates EBs with period variations, among which we identified 63 EBs with cyclic variations and 63 EBs with more likely quadratic behavior. For the first group assuming that the period modulation is caused by a third companion, we calculated the mass function, the period and the LTTE amplitude (Irwin, 1959) assuming zero eccentricity, i 3 = 90 • and M 12 ∼ 2 M and the parameters errors (Papageorgiou & Christopoulou, 2015). In addition, out of these 12 are low-mass candidates (Papageorgiou et al, 2018) and have their initial parameters derived by EBAI or the template method (Papageorgiou et al, 2019) whereas only four have already shown trends of maximum brightness modulation (Papageorgiou et al, 2018).…”