A fresh insight into the evolutionary status and third body hypothesis of the eclipsing binaries AD Andromedae, AL Camelopardalis, and V338 Herculis

Abstract

Aims. We aim to derive the absolute parameters of the components of AD And, AL Cam, and V338 Her, interpret their orbital period changes and discuss their evolutionary status. Methods. New and complete multi-filter light curves of the eclipsing binaries AD And, AL Cam, and V338 Her were obtained and analysed with modern methods. Using all reliably observed times of minimum light, we examined orbital period irregularities using the least squares method. In addition, we acquired new spectroscopic observations during the secondary eclipses for AL Cam and V338 Her. Results. For AL Cam and V338 Her, we derive reliable spectral types for their primary stars. Statistical checks of orbital period analysis for all systems are very reassuring in the cases of V338 Her and AD And, although less so for AL Cam. The LIght-Time Effect (LITE) results are checked by inclusion of a third light option in the photometric analyses. Light curve solutions provide the means to calculate the absolute parameters of the components of the systems and reliably estimate their present evolutionary status. Conclusions. AL Cam and V338 Her are confirmed as classical Algols of relatively low mass in similar configurations. Unlike AL Cam, however, V338 Her is still transferring matter between its components, raising interest in the determinability of the evolutionary histories of Algols. AD And is found to be a detached system in which both close stars are of age ∼10 9 yr and is probably a "non-classical" young triple, at an interesting stage of its dynamical evolution.

Period variations of Algol-type eclipsing binaries AD And, TWCas and IV Cas

“…It is necessary to note that the relative statistical error of Q is almost 90%, what degrades its significance. We have tried also solution with no Q and we surprisingly obtained results with worse Our solution imply minimal 3 rd body mass (for i 3 = 90 • ) of ∼ 2.33 M ⊙ , using absolute parameters from Liakos et al (2012). This would yield the third light about 15% to the total luminosity of the system.…”

“…Giuricin & Mardirossian (1981) published photometric parameters of the system and concluded that both components have almost the same radii, masses, temperatures and luminosities with orbital inclination i = 81.9 • ± 0.4 • , which was confirmed by Liakos et al (2012). The period variations of AD And were investigated by several authors (Walker 1957;Ruciński 1966;Frieboes-Conde & Herczeg 1973;Liao & Qian 2009;Liakos et al 2012). The last mentioned authors determined period of the third body to be 14.3 years and its mass function f (m) = 0.183 M ⊙ .…”

“…This would yield the third light about 15% to the total luminosity of the system. But the third light resulting from light curve analysis (Liakos et al 2012) is about 3%. This difference can be explained with the assumption that the 3 rd star is actually binary system with two solar-mass components as mentioned by Liakos et al (2012).…”

“…With previously described approach we Table 3: Parameters of the 3 rd body orbit from O − C diagram analysis of AD And and comparison with previous studies, P -orbital period of eclipsing pair, T 0 -initial minimum, Q -quadratic term, P 3 -orbital period of the 3 rd body, t 03 -pericenter passage, a sin i 3 -projected semi-major axis of the orbit, e 3 -eccentricity, ω 3 -the longitude of the periastron, f (M 3 ) -the mass function, χ 2 -sum of squares of the best fit, χ 2 /n -reduced sum of squares (n -number of data points), errors are given in parenthesis. (2009), (2) - Liakos et al (2012) can find the best global solution, but its statistical significance strongly depends on number of steps in MCMC simulation, number of generations and size of population used in genetic algorithms. The discussion about selection of proper values is given in Gajdoš & Parimucha (2018).…”

“…Cannon (1934) classified star as a F-type object, later classification of Hill et al (1975) gave spectral type range from B8 to A0. Giuricin & Mardirossian (1981) published photometric parameters of the system and concluded that the both components have almost the same radii, masses, temperatures and luminosities with orbital inclination i = 81.9 ± 0.4 • , what was confirmed by Liakos et al (2012). The period variations of AD And were investigated by several authors (Whitney 1957;Rucinsky 1966;Frieboes-Conde & Herczeg 1973;Liao & Qian 2009;Liakos et al 2012).…”