The CCD photometric study of the newly identified RS CVn binary star V1034 Hercules

This paper presents a new CCD Bessell VR_cI_c light curves and photometric analysis of the newly discovered RS CVn type eclipsing binary star V1034 Her. The light curves were obtained at the Çanakkale Onsekiz Mart University Observatory in 2006. Variations of the orbital period of the system were firstly studied. The (O − C) diagram with a low range of observing time of about 20 years shows an upward parabola, which indicates a secular increase in the orbital period of the system. The light curves are generally those of detached eclipsing binaries; however, there are large asymmetries between maxima. The VR_cI_c light curves were analysed with two different fitting procedures: Wilson–Devinney method supplemented with a Monte Carlo type algorithm and Information Limit Optimization Technique (ILOT). Our general results find V1034 Her. as a well detached system, in which the components are filling 65% of their Roche lobes. Light curve asymmetries of the system are explained in terms of large dark starspots on the primary component. The primary star shows a long-lived spot distribution with active longitudes in the same hemisphere.     

The 2006/2007 photometric activity of three chromospherically active stars: V2075 Cyg,FG UMa and BM CVn

We present new multiband CCD photometric observations of three chromospherically active stars with long periods (V2075 Cyg, FG UMa and BM CVn). The observations were made at the Çanakkale Onsekiz Mart University Observatory in 2006 and 2007. We analyzed BVRI (Bessell) CCD observations of these three RS CVn-type SB1 binaries with the following three steps: (i) Photometric rotation periods were obtained by analyzing their light variations with a differential corrections method and a Fourier transform technique. (ii) Light variations, observed over three or more consecutive orbital cycles, were investigated by using dark (cool) spot models with the program SPOT. (iii) Surface differential rotation coefficients for the primary components of these binaries were derived using our own photometric periods together with orbital periods taken from the literature.     

Astrometric Solution of the Multiple System Xy Leo

An astrometric solution, together with time of minimum analysis, has been made for the multiple system XY Leonis (HIP 49136) to identify the properties of the remote companion to the eclipsing pair (AB). From this solution, we derive the inclination of the wide orbit (AB-cd) as 94.4^∘± 0.2^∘, angle of nodes as 247.3^∘± 0.2^∘, and the mass of the wide component (the dwarf binary cd) as 0.98 ± 0.2 M_⊙. This study confirms that the light travel time effect can explain the sinusoidal O−C variation of the eclipsing system.     

Multi-Facility Study of the Algol-Type Binary δ Librae

Various branches of observational information, and related physical problems concerning the bright, relatively close, Algol binary δ Lib are discussed. Times of minimum light confirm the classical Algol status, which, combined with the optical and IR photometry of Lazaro et al. (2002), provide the basis for a good understanding of the system’s basic parameters. New spectroscopy from the Coudé spectrograph of the Rozhen Observatory (Bulgaria) allows further information on the model and the mass transfer process. Very high resolution radio observations would also have much to reveal about astrophysics of the semi-detached configuration, not only directly, by informing about the outermost envelopes of the components, but indirectly through high accuracy positional information. We show how this may be related to careful period and astrometric studies. δ Lib thus provides a rich source of information on the astrophysics of the Algol configuration.     

Photometric analysis of the eclipsing binary V1425 Cygni

Photoelectric B and V light curves of the eclipsing binary V1425 Cygni were analyzed by the method of Wilson-Devinney. The system was found to be a semi-detached binary where the secondary component (less massive and cooler) fills its Roche lobe.     

First period analyses of five neglected Algol-type eclipsing binaries: TT And, V342 Aql, RW Cap, BZ Cas and TW Lac

We present the first study of the orbital period variations of five neglected Algol-type eclipsing binaries TT And, V342 Aql, RW Cap, BZ Cas and TW Lac, using their O–C diagrams gathered from all available times of eclipse minima. These O–C diagrams indicate that short term periodic variations superimposed on secular period increases as expected in mass transferring Algols. However, due to short time coverage of the data, the secular period increase is not clear in the case of BZ Cas and V342 Aql. The secular period increase is interpreted in terms of the combined effect of mass transfer between the components of the system and the mass loss by a stellar wind from the system. The mass transfer rates from the less massive secondary components to the more massive primaries for non-conservative cases would be about 10⁻⁷M/yr and 10⁻⁸M/yr for RW Cap and V342 Aql, respectively, and 10⁻⁹M/yr for TT And and TW Lac. Therefore, the Algol systems RW Cap and V342 Aql have the largest mass transfer rate, which could be in Case AB type, while those of the Algol systems TT And and TW Lac display the slow mass transfer rate and they could be in Case B type. The sinusoidal forms of the orbital period variations of all five Algol systems can be due to either by the light-time effects due to unseen components in these systems, or by the cyclic magnetic activity effects of the cool secondary components. The possible third bodies in all five Algol binaries would have masses larger than one solar mass. If these hypothetical large massive third bodies were normal stars, they should be detectable. Therefore, new photometric and spectroscopic observations of these systems and careful analyses of those data are required. Otherwise, the cyclic magnetic activity effects of the secondary components could be the basis of a working hypothesis in explaining the cyclic period variations of these systems.     

Probabilistic Appraisal of Earthquake Hazard Parameters Deduced from a Bayesian Approach in the Northwest Frontier of the Himalayas

A straightforward Bayesian statistic is applied in five broad seismogenic source zones of the northwest frontier of the Himalayas to estimate the earthquake hazard parameters (maximum regional magnitude M _max, β value of G–R relationship and seismic activity rate or intensity λ). For this purpose, a reliable earthquake catalogue which is homogeneous for M _W ≥ 5.0 and complete during the period 1900 to 2010 is compiled. The Hindukush–Pamir Himalaya zone has been further divided into two seismic zones of shallow (h ≤ 70 km) and intermediate depth (h > 70 km) according to the variation of seismicity with depth in the subduction zone. The estimated earthquake hazard parameters by Bayesian approach are more stable and reliable with low standard deviations than other approaches, but the technique is more time consuming. In this study, quantiles of functions of distributions of true and apparent magnitudes for future time intervals of 5, 10, 20, 50 and 100 years are calculated with confidence limits for probability levels of 50, 70 and 90 % in all seismogenic source zones. The zones of estimated M _max greater than 8.0 are related to the Sulaiman–Kirthar ranges, Hindukush–Pamir Himalaya and Himalayan Frontal Thrusts belt; suggesting more seismically hazardous regions in the examined area. The lowest value of M _max (6.44) has been calculated in Northern-Pakistan and Hazara syntaxis zone which have estimated lowest activity rate 0.0023 events/day as compared to other zones. The Himalayan Frontal Thrusts belt exhibits higher earthquake magnitude (8.01) in next 100-years with 90 % probability level as compared to other zones, which reveals that this zone is more vulnerable to occurrence of a great earthquake. The obtained results in this study are directly useful for the probabilistic seismic hazard assessment in the examined region of Himalaya.     

Discrimination of earthquakes and quarry blasts in the eastern Black Sea region of Turkey

In recent years, a large number of quarry blasts have been detonated in the eastern Black Sea region. When these blasts are recorded by seismic stations, they contaminate the regional earthquake catalog. It is necessary to discriminate quarry blast records from the earthquake catalogs in order to determine the real seismicity of the region. Earthquakes and quarry blasts can be separated through different methods. These methods should be applied concurrently in order to safely distinguish these events. In this study, we discriminated quarry blasts from earthquakes in the eastern Black Sea region of Turkey. We used 186 seismic events recorded by the Karadeniz Technical University and Bogaziçi University Kandilli Observatory Earthquake Research Institute stations which are Trabzon, Espiye, Pazar, Borçka, Ayd?ntepe, and Gümü?hane between years of 2002 and 2010. For the discrimination of quarry blasts from earthquakes, we used both, statistical methods (calculation of the maximum ratio of S to P waves (S/P), complexity (C)) and spectral methods (spectrogram calculation). These methods included measuring the maximum amplitude S/P, C, spectral ratio, and time-frequency analysis. We especially relied on two-dimensional time-frequency analysis methods to discriminate quarry blasts from earthquakes in Turkey. As a result of this study, 68 % of the examined seismic events were determined to be quarry blasts and 32 % to be earthquakes. The earthquakes occurring on land are related to small faults and the blasts are concentrated in large quarries. Nearly 40 % of the earthquakes occurred in the Black Sea, most of them are related to the Black Sea thrust belt, where the largest earthquake was observed in the time period studied. The areas with the largest earthquake potential in the eastern Black Sea region are in the sea.