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Csávoly, Hungary

Kovacs J.,University of Pecs | Sajo I.,University of Pecs | Marton Z.,MTA PTE High Field Terahertz Research Group | Marton Z.,University of Pecs | And 6 more authors.
Planetary and Space Science

We report here for the first time the composition and mineralogical studies on a new meteorite, which was found in August 2012 near the village of Csátalja, Hungary (46°0'21-N; 18°59'27'E). The Csátalja meteorite is classified as a H4-5 ordinary chondrite with shock stage S2 and a degree of weathering W1 and the total mass is 15 kg. The Csátalja meteorite is characterized by well-defined chondrules composed either of olivine or pyroxene. X-ray diffractogram shows the primary phases olivine, pyroxene, kamacite, and albite. Metal particles were extracted from the bulk powdered samples exhibit only kamacite and small amounts of the intergrowth taenite/kamacite. Raman spectra of forsterite indicate that Csátalja meteorite suffered from relatively low shock pressure regime. The texture of chondrules varies from nonporphyritic (e.g., barred olivine, radial pyroxene) to porphyritic ones (e.g., granular olivine as well as olivine pyroxene). The meteorite name has not yet approved by the Nomenclature Committee of the Meteoritical Society. © 2014 Elsevier Ltd. All rights reserved. Source

Borkovits T.,Baja Astronomical Observatory | Paragi Z.,Joint Institute for VLBI in Europe | Paragi Z.,MTA Research Group for Physical Geodesy and Geodynamics | Csizmadia S.,German Aerospace Center
Journal of Physics: Conference Series

Both theoretical and indirect observational evidences suggest that most of the closest binary stars with orbital periods of few days (as well as hot Jupiter-type exoplanets) formed with an original separation larger by 1-2 orders of magnitude than the present one. Consequently, an orbital shrinking mechanism(s) must be present that extracts the angular momentum from a primordial binary. From the possible mechanisms studied in the literature we describe the so-called 'Kozai cycles combined with tidal friction' (KCTF), which gives some definite predictions for the statistical properties of the orbital elements in such close binaries. Due to the recent powerful observing techniques, such as optical and radio (VLBI) interferometry, we can already peer inside such close binaries, so we have some opportunity to check these predictions. We examine the practical details, constraints, restrictions about the inquiring of the necessary information from specific triple systems by interferometric (as well as polarimetric) observations. Finally, to illustrate this we give a brief description of our recent combined optical and radio interferometric measurements of Algol. © 2010 IOP Publishing Ltd. Source

Biro I.B.,Baja Astronomical Observatory | Nuspl J.,Hungarian Academy of Sciences
Monthly Notices of the Royal Astronomical Society

We present the dynamic eclipse mapping method designed specifically to reconstruct the surface intensity patterns of non-radial stellar oscillations on components of eclipsing binaries. The method needs a geometric model of the binary, accepts the light curve and the detected pulsation frequencies on input, and on output yields estimates of the pulsation patterns, in the form of images, thus allowing a direct identification of the surface mode numbers (ℓ, m). Since it has minimal modelling requirements and can operate on photometric observations in arbitrary wavelength bands, dynamic eclipse mapping is well suited to analyse the wide-band time series collected by space observatories. We have investigated the performance and the limitations of the method through extensive numerical tests on simulated data, in which almost all photometrically detectable modes with a latitudinal complexity ℓ- |m| ≤ 4 were properly restored. The method is able by its nature to simultaneously reconstruct multimode pulsations from data covering a sufficient number of eclipses as well as pulsations on components with a tilted rotation axis of a known direction. It can also be applied in principle to isolate the contribution of hidden modes from the light curve. Sensitivity tests show that moderate errors in the geometric parameters and the assumed limb darkening can be partially tolerated by the inversion, in the sense that the lower degree modes are still recoverable. Tidally induced or mutually resonant pulsations, however, are an obstacle that neither the eclipse mapping nor any other inversion technique can ever surpass. We conclude that, with reasonable assumptions, dynamic eclipse mapping could be a powerful tool for mode identification, especially in moderately close eclipsing binary systems, where the pulsating component is not seriously affected by tidal interactions so that the pulsations are intrinsic to them, and not a consequence of the binarity. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS. Source

Tran K.,Kavli Institute for Astrophysics and Space Research | Levine A.,37 575 Mit Kavli Institute For Astrophysics And Space Research | Rappaport S.,Kavli Institute for Astrophysics and Space Research | Borkovits T.,Baja Astronomical Observatory | And 4 more authors.
Astrophysical Journal

We report a study of the eclipse timing variations in contact binary systems, using long-cadence lightcurves from the Kepler archive. As a first step, observed minus calculated (O-C) curves were produced for both the primary and secondary eclipses of some 2000 Kepler binaries. We find ∼390 short-period binaries with O-C curves that exhibit (1) random walk-like variations or quasi-periodicities, with typical amplitudes of ±200-300 s, and (2) anticorrelations between the primary and secondary eclipse timing variations. We present a detailed analysis and results for 32 of these binaries with orbital periods in the range of 0.35 ± 0.05 days. The anticorrelations observed in their O-C curves cannot be explained by a model involving mass transfer, which, among other things, requires implausibly high rates of ∼0.01 MȮ yr-1. We show that the anticorrelated behavior, the amplitude of the O-C delays, and the overall random walk-like behavior can be explained by the presence of a starspot that is continuously visible around the orbit and slowly changes its longitude on timescales of weeks to months. The quasi-periods of ∼50-200 days observed in the O-C curves suggest values for k, the coefficient of the latitude dependence of the stellar differential rotation, of ∼0.003-0.013. © 2013. The American Astronomical Society. All rights reserved. Source

Hareter M.,Konkoly Observatory | Paparo M.,Konkoly Observatory | Weiss W.,University of Vienna | Garcia Hernandez A.,University of Porto | And 12 more authors.
Astronomy and Astrophysics

Context. Pulsating stars in binary systems are ideal laboratories to test stellar evolution and pulsation theory, since a direct, model-independent determination of component masses is possible. The high-precision CoRoT photometry allows a detailed view of the frequency content of pulsating stars, enabling detection of patterns in their distribution. The object HD 51844 is such a case showing periastron brightening instead of eclipses. Aims. We present a comprehensive study of the HD 51844 system, where we derive physical parameters of both components, the pulsation content and frequency patterns. Additionally, we obtain the orbital elements, including masses, and the chemical composition of the stars. Methods. Time series analysis using standard tools was employed to extract the pulsation frequencies. Photospheric abundances of 21 chemical elements were derived by means of spectrum synthesis. We derived orbital elements both by fitting the observed radial velocities and the light curves, and we did asteroseismic modelling as well. Results. We found that HD 51844 is a double lined spectroscopic binary. The determined abundances are consistent with δ Delphini classification. We determined the orbital period (33.498 ± 0.002 d), the eccentricity (0.484 ± 0.020), the mass ratio (0.988 ± 0.02), and the masses to 2.0 ± 0.2 M for both components. Only one component showed pulsation. Two p modes (f22 and f36) and one g mode (forb) may be tidally excited. Among the 115 frequencies, we detected triplets due to the frequency modulation, frequency differences connected to the orbital period, and unexpected resonances (3:2, 3:5, and 3:4), which is a new discovery for a δ Sct star. The observed frequency differences among the dominant modes suggest a large separation of 2.0-2.2 d-1, which are consistent with models of mean density of 0.063 g cm-3, and with the binary solution and TAMS evolutionary phase for the pulsating component. The binary evolution is in an intermediate evolutionary phase; the stellar rotation is super-synchronised, but circularisation of the orbit is not reached. © ESO, 2014. Source

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