FS Aurigae is famous for a variety of uncommon and puzzling periodic photometric and spectroscopic variabilities which do not fit well into any of the established sub-classes of cataclysmic variables. Here we present preliminary results of long-term monitoring of the system, conducted during the 2010-2011 observational season. We show that the long-term variability of FS Aur and the character of its outburst activity may be caused by variations in the mass transfer rate from the secondary star as the result of eccentricity modulation of a close binary orbit induced by the presence of a third body on a circumbinary orbit.

We present basic information about package SPHOTOM for an automatic multicolour photometry. This package is in development for the creation of a photometric pipe-line, which we plan to use in the near future with our new instruments. It could operate in two independent modes, (i) GUI mode, in which the user can select images and control functions of package through interface and (ii) command line mode, in which all processes are controlled using a main parameter file. SPHOTOM is developed as a universal package for Linux based systems with easy implementation for different observatories. The photometric part of the package is based on the Sextractor code, which allows us to detect all objects on the images and perform their photometry with different apertures. We can also perform astrometric solutions for all images for a correct cross-identification of the stars on the images. The result is a catalogue of all objects with their instrumental photometric measurements which are consequently used for a differential magnitudes calculations with one or more comparison stars, transformations to an international system, and determinations of colour indices.

The preliminary results of a study of a neglected, relatively bright, short-periodic (P=0.48 d), near contact eclipsing binary BS Vulpeculae is given. We present our new complete (BVRI) light curves, and physical parameters of the system based on them, derived by the 2003 version of the Wilson–Van Hamme code.

This paper presents the results of the analysis of (O-C) diagrams of four eclipsing variables. The diagrams are based on times of minima collected in the Cracow database, which contains times of minima found in the literature, from observations at Mt. Suhora and Ulupinar Observatories, or determined using publicly-available photometric surveys (NSVS, ASAS etc).

Intermediate polars represent a major fraction of all cataclysmic variables detected by INTEGRAL in hard X-rays. Nevertheless, only 25% of all known intermediate polars have been was detected in hard X-rays. This fact can be related to the activity state of these close interacting binaries. Multi-frequency (optical to X-ray) investigation of intermediate polars is essential to understand the physical mechanisms responsible for the observed activity of these objects.

We present the precise multicolour photometry of the eclipsing variable EQ Boo (P = 5d.43, V = 8m.8), which is component “A” of the visual double star ADS 9422 (F7 V+G0 V, ρ = 1.3”, Δmag = 0.7). From the analysis of these data, we can propose the existence of the fourth component with a late spectral type.

We present long-term observations of magnetic cataclysmic variables AM Her, AN UMa, AR UMa, DP Leo, and V1309 Ori obtained with the ROTSEIIId telescope. All data have been analysed and preliminary results indicate periods of 170 days, 217 days, and 180 days for AM Her, AN UMa, and AR UMa, respectively.

The eclipsing variable stars GSC 44870347 and GSC 4513 2537 are recently discovered binary systems (Otero et al., 2006) with orbital periods 1d.99 and 6d.33 days. We carried out the photometric observations of these eclipsing binaries from 2009-2010 using a CCD-array at the Tien-Shan Observatory in Kazakstan, at the Crimea Station of the Sternberg Astronomical Institute, at the Astrokolkhoz Observatory in New Mexico (AAVSO), while the spectrophotometric observations were obtained at the Starlight Farm Observatory in Barnesville, USA.

High resolution spectral observations of ϵ Aur were carried out in the near-IR spectral range. Observations were obtained with the Coudé-spectrograph of the 2m RCC telescope at National Astronomical Observatory Rozhen and cover all main phases of the current eclipse. Results revealed for the first time absorption components in O I and Ca II triplets and variations of N I lines. Estimation of the electron density was done using lines from the Paschen series of hydrogen.

Low mass stars in binaries are frequently used as unique tools to determine and establish fundamental stellar parameters. The need for their study and understanding has led to developing new instruments, new observational techniques and improved theoretical models. The relatively recent discovery of exoplanets and their study as the low-mass constituents around other stars is now opening new horizons in binary research. Here, I examine the most common observational challenges in studying low mass binaries across the electromagnetic spectrum.

Nearly 500 brown dwarfs have been discovered in recent years. The majority of these brown dwarfs exist in the solar neighborhood, yet determining their fundamental properties (mass, age, temperature & metallicity) has proved to be quite difficult, with current estimates relying heavily on theoretical models. Binary brown dwarfs provide a unique opportunity to empirically determine fundamental properties, which can then be used to test model predictions. In addition, the observed binary fractions, separations, mass ratios, & orbital eccentricities can provide insight into the formation mechanism of these low-mass objects. I will review the results of various brown dwarf multiplicity studies, and will discuss what we have learned about the formation and evolution of brown dwarfs by examining their binary properties as a function of age and mass.

Extrasolar planets in binary and multiple star systems have become a noticeable niche with about 50 planets among over 500 known. Here we however focus on a particular subset of exoplanets in binary star systems — circumbinary planets. They have the unique advantage that a search for circumbinary planets does also significantly contribute to the understanding of their parent stars. We review what is currently known about circumbinary planets and then introduce our two projects aimed at detecting circumbinary planets: The TATOOINE project to find circumbinary planets around non-eclipsing double-lined spectroscopic binary stars with precision radial velocities, and the SOLARIS project to detect circumbinary planets with the timing of eclipses of eclipsing binary stars. For the SOLARIS project, we were granted 2.6 million USD to establish a network of at least four robotic 0.5-m telescopes on three continents (Australia, Africa and South America) to carry out precision photometry of a sample of eclipsing binary stars. We expect that both projects will have a large impact also on the observational stellar astronomy.

Here, we summarise the conditions that might lead to the formation of a bow shock surrounding a planet's magnetosphere. Such shocks are formed as a result of the interaction of a planet with its host star wind. In the case of close-in planets, the shock develops ahead of the planetary orbit. If this shocked material is able to absorb stellar radiation, the shock signature can be revealed in (asymmetric) transit light curves. We propose that this is the case of the gas giant planet WASP-12b, whose near-UV transit observations have detected the presence of an extended material ahead of the planetary orbit. We show that shock detection through transit observations can be a useful tool to constrain planetary magnetic fields.

We demonstrate that moderate exoplanet radial velocity searches are often subject to the effect of the correlated (red) radial velocity noise. When disregarded, this effect may induce strong distortions in the results of the time series analysis and, ultimately, can even lead to false planet detections. We construct a maximum-likelihood algorithm, which is able to manage this issue rather efficiently.

We can show that analysis of the (O-C) diagram is a powerful method of detecting new bodies in binary systems. For this purpose we need very symmetric minima with precisely determined shapes. In the case of good covering by observations with high time resolution, it is possible to determine the times of such minima with sufficient accuracy. In the case of V471 Tau, the (O-C) diagram gave us residua which can be explained by the presence of a fourth body with substellar mass in the system.

The orbital period is one of the most accessible observables of a cataclysmic variable. It has been a concern for many years that the orbital period distribution of the known systems does not match that predicted by evolutionary theory. The sample of objects discovered by the Sloan Digital Sky Survey has changed this: it shows the long-expected predominance of short-period objects termed the ‘period spike’. The minimum period remains in conflict with theory, suggesting that the angular momentum loss mechanisms are stronger than predicted.

We analyse the chromospherical activity of stars with extrasolar planets and search for a possible correlation between the equivalent width of the core of the Ca II K line and orbital parameters of the planet. We found statistically significant evidence that the equivalent width of the Ca II K line reversal, which originates in the stellar chromosphere, depends on the orbital period Porb of the exoplanet. Planets orbiting stars with Teff < 5 500 K and with Porb < 20 days generally have much stronger emission than planets at similar temperatures but at longer orbital periods. Porb = 20 days marks a sudden change in behaviour, which might be associated with a qualitative change in the star-planet interaction.

The modelling of the insufficient orbital elements of extra-solar planets (EPs) revolving around one component in a binary star system is investigated in the present paper. This problem is considered in the frame of the three-body problem using the analytical theory of Orlov & Solovaya (1998). In the general case, the motion is defined by the masses of the components and by the six pairs of the initial values of the Keplerian elements. For EPs, it is not possible to obtain the complete set of elements for the orbit, in particular, the ascending node and the angle of the inclination. So, it is possible the two different variants of orbital evolution of EPs depend on the initial conditions. In one case, the orbit is unstable. Using the stability conditions of Solovaya & Pittich (2004), which are presented by the angle of the mutual inclination of the orbits between the EP and distant star, we varied unknown angular elements and defined the regions with possible values of the elements for which the motion of EP stays stable. We applied these calculations to the particular specific EPs: HD19994b, HD196885Ab and HD222404b.

I briefly review the history and prospects for the study of eclipsing binary star systems from space-based observatories. The benefits of shifting to space satellites lie in the high precision and cadence achievable, as well as the ability to access wavelength regions which are unattainable from the ground. Whilst small amounts of data on eclipsing binaries were obtained by the Voyager, IUE, OAO-II, Hipparcos and MOST, the more recent CoRoT and Kepler missions were the first to provide extensive data on large numbers of systems. The future holds the prospect of the PLATO satellite, which will go bigger, better and brighter.

The derived physical properties of the known transiting extrasolar planetary systems come from a variety of sources, and are calculated using a range of different methods so are not always directly comparable. I present a catalogue of the physical properties of 58 transiting extrasolar planet and brown dwarf systems which have been measured using homogeneous methods, resulting in quantities which are internally consistent and well-suited to detailed statistical study. The main results for each object, plus a critical compilation of literature values for all known systems, have been placed in an online catalogue. TEPCat can be found at http://www.astro.keele.ac.uk/~jkt/tepcat/