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We present 126 eclipsing binary candidates among 4683 Catalina Sky Surveys (CSS) detached and semi-detached eclipsing binary systems (EBs) showing cyclic or quadratic period variations over a 12 yr time span. By using inverse Gaussian profiles of the eclipses coupled with a Markov chain Monte Carlo procedure, times of minima (ToM) were calculated and diagrams with eclipse timing variations (ETVs) were constructed. Numerical tests were performed, involving synthetic EBs with period variations generated by the PHOEBE 2.0 engine and actual data for EBs with well-known period variations from the literature, to verify that the calculation of ToM variations for our CSS systems is reliable. A total of 63 out of the 126 EBs show likely cyclic ETVs, while the remainder present quadratic behaviour instead. Periods, amplitudes, period change rates, and associated errors were determined by using sinusoidal and parabolic models. 12 out of the 63 EBs (19 per cent) that appear to exhibit periodic ETVs are low-mass candidates. Additionally, four out of 126 also have maximum quadrature light variations. The possibility that the cyclic variations are caused by the light traveltime effect due to the presence of a tertiary companion is investigated. The possible nature of the quadratic ETVs is also discussed.

This paper presents a multidisciplinary design optimization framework applied to the development of unmanned aerial vehicles with a focus on radar signature and sensor performance requirements whil ...

The discovery and characterization of Algol eclipsing binaries (EAs) provide an opportunity to contribute for a better picture of the structure and evolution of low-mass stars. However, the cadence of most current photometric surveys hinders the detection of EAs since the separation between observations is usually larger than the eclipse(s) duration and hence few measurements are found at the eclipses. Even when those objects are detected as variable, their periods can be missed if an appropriate oversampling factor is not used in the search tools. In this paper, we apply this approach to find the periods of stars cataloged in the Catalina Real-Time Transient Survey (CRTS) as EAs having unknown period (EA$_{\rm up}$). As a result, the periods of $\sim 56\%$ of them were determined. Eight objects were identified as low-mass binary systems and modeled with the Wilson \& Devinney synthesis code combined with a Monte-Carlo Markov Chain optimization procedure. The computed masses and radii are in agreement with theoretical models and show no evidence of inflated radii. This paper is the first of a series aiming to identify suspected binary systems in large surveys., 11 pages, 7 figures

We present an updated catalog of 4680 northern eclipsing binaries (EBs) with Algol-type light-curve (LC) morphology (i.e., with well-defined beginnings and ends of primary and secondary eclipses), using data from the Catalina Sky Surveys. Our work includes revised period determinations, phenomenological parameters of the LCs, and system morphology classifications based on machine-learning techniques. While most of the new periods are in excellent agreement with those provided in the original Catalina catalogs, improved values are now available for ~10% of the stars. A total of 3456 EBs were classified as detached and 449 were classified as semi-detached, while 145 could not be classified unambiguously into either subtype. The majority of the SD systems seem to be comprised of short-period Algols. By applying color criteria, we searched for K- and M-type dwarfs in these data, and present a subsample of 609 EB candidates for further investigation. We report 119 EBs (2.5% of the total sample) that show maximum quadrature light variations over long timescales, with periods bracketing the range 4.5–18 years and a fractional luminosity variance range of 0.04–0.13. We discuss possible causes for this, making use of models of variable starspot activity in our interpretation of the results.

This paper presents a Multidisciplinary Design Optimization (MDO) framework that is intended to be employed in the early design stages of Unmanned Aerial Vehicles (UAVs) when the primary focus is o ...

The O’Connell effect is one of the most perplexing challenges in binary studies as it has not been convincingly explained. Furthermore, a simple method to obtain essential parameters for eclipsing binaries exhibiting this effect and to extract information describing the asymmetry in the light curve maxima is needed. We have developed an automated program that characterizes the morphology of light curves by depth of both minima, height of both maxima and curvature outside the eclipses.

Our thinking about eclipsing binary stars has undergone a tremendous change in the last decade. Eclipsing binary stars are one of nature’s best laboratories for determining the fundamental physical properties of stars and thus for testing the predictions of theoretical models. Some of the largest ongoing variable star surveys include the Catalina Real-time Transient Survey (CRTS) and the VISTA Variables in the Vía Láctea survey (VVV). They both contain a large amount of photometric data and plenty of information about eclipsing binaries that wait to be extracted and exploited. Here we briefly describe our efforts in this direction.