A5034734184- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Space Exploration and Technology
- Planetary Science and Exploration
- Astrophysical Phenomena and Observations
- Software Reliability and Analysis Research
- Solar and Space Plasma Dynamics
- Software Engineering Research
- History and Developments in Astronomy
- Spacecraft and Cryogenic Technologies
- Solidification and crystal growth phenomena
- Hungarian Social, Economic and Educational Studies
- High-pressure geophysics and materials
- Cloud Computing and Resource Management
- Pulsars and Gravitational Waves Research
- Space Satellite Systems and Control
- Software System Performance and Reliability
- Software-Defined Networks and 5G
- Astronomical and nuclear sciences
- Laser and Thermal Forming Techniques
Ericsson (Hungary)
2016-2025
Konkoly Observatory
2015-2024
Research Centre for Astronomy and Earth Sciences
2015-2024
Eötvös Loránd University
2000-2024
Magyar Agrár- és Élettudományi Egyetem
2024
Obuda University
2024
Hungarian Research Network
2011-2023
University of Pecs
2022
Ericsson (Canada)
2022
West University of Timişoara
2005-2021
Asteroseismology involves probing the interiors of stars and quantifying their global properties, such as radius age, through observationsof normal modes oscillation. The technical requirements for conducting asteroseismology include ultra-high precision measured in photometry parts per million, well nearly continuous time series over weeks to years, cadences rapid enough sample oscillations with periods shortas a few minutes. We report on results from first 43 days observations which unique...
Thousands of exoplanets have now been discovered with a huge range masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface their host star. However, essential nature these remains largely mysterious: there is no known, discernible pattern linking presence, size, or orbital parameters planet its parent We little idea whether chemistry linked formation environment, type star drives physics planet's birth, evolution. ARIEL was conceived observe number...
Mass-loss of red giant branch (RGB) stars is still poorly determined, despite its crucial role in the chemical enrichment galaxies. Thanks to recent detection solar-like oscillations G–K giants open clusters with Kepler, we can now directly determine stellar masses for a statistically significant sample old NGC 6791 and 6819. The aim this work constrain integrated RGB mass-loss by comparing average mass clump (RC) that low-luminosity portion [i.e. L≲L(RC)]. Stellar were determined combining...
Over the duration of Kepler mission, KIC8462852 was observed to undergo irregularly shaped, aperiodic dips in flux up $\sim 20$\%. The dipping activity can last for between 5 and 80 days. We characterize object with high-resolution spectroscopy, spectral energy distribution fitting, radial velocity measurements, imaging, Fourier analyses light curve. determine that is a typical main-sequence F3 V star exhibits no significant IR excess, has very close interacting companions. In this paper, we...
The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds A-F type stars. We present a first general characterization the pulsational behaviour stars as observed in light curves sample 750 candidate propose three main groups to describe variety pulsating stars: gamma Dor, delta Sct, and hybrid assign 63% our one groups, identify remaining part rotationally modulated/active stars, binaries, different spectral type, or that show no clear...
Observations of the pulsations stars can be used to infer their interior structure and test theoretical models. The main-sequence γ Doradus (Dor) δ Scuti (Sct) with masses 1.2–2.5 M☉ are particularly useful for these studies. Dor pulsate in high-order g-modes periods order 1 day, driven by convective blocking at base envelope convection zone. Sct low-order g- p-modes 2 hr, κ mechanism operating He ii ionization Theory predicts an overlap region Hertzsprung–Russell diagram between instability...
The nearly continuous light curves with micromagnitude precision provided by the space mission Kepler are revolutionising our view of pulsating stars. They have revealed a vast sea low-amplitude pulsation modes that were undetectable from Earth. long time base allows an accurate determination frequencies and amplitudes needed for in-depth asteroseismic modeling. However, study to be successful, first estimates stellar parameters need known they can not derived photometry itself. Input...
The analysis of the light curves 48 B-type stars observed by Kepler is presented. Among these are 15 pulsating stars, all which show low frequencies, characteristic slowly B (SPB) stars. Seven also a few weak, isolated high frequencies and they could be considered as SPB/β Cephei (β Cep) hybrids. In cases, frequency spectra quite different from what seen ground-based observations. We suggest that this because most modes degree predicted to unstable in models mid-B find there non-pulsating...
The first detection of the period doubling phenomenon is reported in Kepler RR Lyrae stars Lyr, V808 Cyg and V355 Lyr. Interestingly, all these pulsating show Blazhko modulation. manifests itself as alternating maxima minima pulsational cycles light curve, well through appearance half-integer frequencies located halfway between main pulsation its harmonics frequency spectrum. effect was found to be stronger during certain phases modulation cycle. We were able reproduce bifurcation our...
KOI-13.01, a planet-sized companion in an optical double star was announced as one of the 1235 Kepler planet candidates February 2011. The transit curves show significant distortion that stable over ~130 days time-span data. Here we investigate phenomenon via detailed analyses two components and re-reduction data with pixel-level photometry. Our results indicate KOI-13 is common proper motion binary, rapidly rotating (v sin i ~ 65--70 km/s). We identify host KOI-13.01 conclude curve...
We present the first results of our analyses selected RR Lyrae stars for which data have been obtained by Kepler Mission. As expected, we find a significant fraction RRab to show Blazhko effect, still unexplained phenomenon that manifests itself as periodic amplitude and phase modulations light curve, on time scales typically tens hundreds days. The long span Mission 3.5 yrs, unprecedentedly high precision its provide unique opportunity study stars. Using modulated star observed in roll...
Studying star clusters offers significant advances in stellar astrophysics due to the combined power of having many stars with essentially same distance, age, and initial composition. This makes excellent test benches for verification evolution theory. To fully exploit this potential, it is vital that sample uncontaminated by are not members cluster. Techniques determining cluster membership therefore play a key role investigation clusters. We present results on three Kepler field view based...
Hierarchical triple systems comprise a close binary and more distant component. They are important for testing theories of star formation stellar evolution in the presence nearby companions. We obtained 218 days Kepler photometry HD 181068 (magnitude 7.1), supplemented by groundbased spectroscopy interferometry, which show it to be hierarchical with two types mutual eclipses. The primary is red giant that 45-day orbit pair dwarfs 0.9-day orbit. shows evidence tidally-induced oscillations...
We present the analysis of four first overtone RR Lyrae stars observed with Kepler space telescope, based on data obtained over nearly 2.5 yr. All are found to be multiperiodic. The strongest secondary mode frequency f2 has an amplitude a few mmag, 20–45 times lower than main radial f1. two oscillations have period ratio P2/P1 = 0.612–0.632 that cannot reproduced by any modes. Thus, is non-radial. Modes yielding similar ratios also recently been discovered in other variables RRc and RRd...
In order to benefit from the four year unprecedented precision of Kepler data, we extracted light curves pixel photometric data space telescope for 15 Blazhko RR Lyrae stars. To collect all flux a given target as accurately possible, defined tailor-made apertures each star and quarter. some cases, aperture finding process yielded sub-optimal results, because have been lost even if contains available pixels around star. This fact stresses importance those methods that rely on whole curve...
Abstract Supernova (SN) 2018oh (ASASSN-18bt) is the first spectroscopically confirmed Type Ia supernova (SN Ia) observed in Kepler field. The data revealed an excess emission its early light curve, allowing us to place interesting constraints on progenitor system. Here we present extensive optical, ultraviolet, and near-infrared photometry, as well dense sampling of optical spectra, for this object. SN relatively normal photometric evolution, with a rise time 18.3 ± 0.3 days Δ m 15 ( B ) =...
Compared with previous space-borne surveys, the Transiting Exoplanet Survey Satellite (TESS) provides a unique and new approach to observe solar system objects. While its primary mission avoids vicinity of ecliptic plane by approximately six degrees, scale height debris disk is large enough place various small body populations in field view. In this paper we present first data release photometric analysis TESS observations bodies, focusing on bright end observed main-belt asteroid Jovian...
We present the first results from Transiting Exoplanet Survey Satellite (TESS) on rotational and pulsational variability of magnetic chemically peculiar A-type stars. analyse TESS 2-min cadence data sectors 1 2 a sample 83 Five new rapidly oscillating Ap (roAp) stars are announced. One these pulsates with periods around 4.7 min, making it shortest period roAp star known to date. Four out five multiperiodic. Three singly periodic one show presence mode splitting. Individual frequencies...
Abstract The Vera C. Rubin Legacy Survey of Space and Time (LSST) holds the potential to revolutionize time domain astrophysics, reaching completely unexplored areas Universe mapping variability scales from minutes a decade. To prepare maximize LSST data for exploration transient variable Universe, one four pillars science, Transient Variable Stars Science Collaboration, eight Collaborations, has identified research interest requirements, paths enable them. While our roadmap is...
We present our analysis of Kepler observations 29 RR Lyrae stars, based on 138 d observation. report precise pulsation periods for all stars. Nine these stars had incorrect or unknown in the literature. 14 exhibit both amplitude and phase Blazhko modulations, with ranging from 27.7 to more than 200 d. For V445 Lyr, a longer secondary variation is also observed addition its 53.2-d period. The unprecedented precision photometry has led discovery smallest modulations detected so far. Moreover,...
Nineteen of the ~40 RR Lyr stars in Kepler field have been identified as candidate non-Blazhko (or unmodulated) stars. In this paper we present results Fourier decomposition time-series photometry these acquired during first 417 days operation (Q0-Q5) telescope. parameters based on ~18400 long-cadence observations per star (and ~150000 short-cadence for FN and AW Dra) are derived. None shows recently discovered `period-doubling' effect seen Blazhko variables; however, KIC 7021124 has found...
<i>Context. <i/>The CoRoT – Convection Rotation and planetary Transits space mission is a great opportunity for monitoring stars with excellent time-sampling unprecedented photometric precision up to 150 days. As an important benefit, high-quality RR Lyrae light curves are obtained quasi-uninterrupted coverage over several pulsation Blazhko cycles. <i>Aims. <i/> The effect in unsolved problem of astrophysics. We used the high-precision data contribute more precise knowledge explain possible...
Asteroseismology of stars in clusters has been a long-sought goal because the assumption common age, distance, and initial chemical composition allows strong tests theory stellar evolution. We report results from first 34 days science data Kepler Mission for open cluster NGC 6819—one four field view. obtain clear detections solar-like oscillations red giants are able to measure large frequency separation, Δν, maximum oscillation power, νmax. find that asteroseismic parameters allow us test...
Context: Four open clusters are present in the Kepler field of view and timeseries nearly a year length now available. These allow us to derive asteroseismic global oscillation parameters red-giant stars three NGC 6791, 6819 6811. From these effective temperatures, we mass, radii luminosities for as well red giants. Aims: We study influence evolution metallicity on observed populations. Methods: The derived using different published methods temperatures from 2MASS colours. observational...