179 citations · 1k across the 17 of their papers we have counts for
14 papers · 1 filter
Chaotic dynamics in the pulsation of DF Cygni, as observed by Kepler
E. Plachy, A. Bódi, Z. Kolláth
Pulsations of RV Tauri-type variable stars can be governed by chaotic dynamics. However, observational evidence for this happening is usually hard to come by. Here we use the conti…
Magnetic cycles at different ages of stars
K. Oláh, Zs. Kővári, K. Petrovay +4
We study the different patterns of interannual magnetic variability in stars on or near the lower main sequence, approximately solar-type (G-K dwarf) stars in time series of 36 yea…
Evaluating the summer night sky brightness at a research field site on Lake Stechlin in northeastern Germany
Andreas Jechow, Franz Hölker, Zoltán Kolláth +2
We report on luminance measurements of the summer night sky at a field site on a freshwater lake in northeastern Germany (Lake Stechlin) to evaluate the amount of artificial skyglo…
The unique dynamical system underlying RR Lyrae pulsations
Zoltán Kolláth
Hydrodynamic models of RR Lyrae pulsation display a very rich behaviour. Contrary to earlier expectations, high order resonances play a crucial role in the nonlinear dynamics repre…
Low-dimensional chaos in RR Lyrae models
E. Plachy, Z. Kolláth, L. Molnár
The recent precise photometric observations and successes of the modelling efforts transformed our picture of the pulsation of RR Lyrae stars. The discovery of additional frequenci…
Elimination of long-term variation from chaotic light curves
E. Plachy, Z. Kolláth
We performed a comparative dynamical investigation of chaotic test data using the global flow reconstruction method. We demonstrate that large-amplitude, long-term variations may h…
Nonlinear asteroseismology of RR Lyrae
L. Molnár, Z. Kolláth, R. Szabó +4
The observations of the Kepler space telescope revealed that fundamental-mode RR Lyrae stars may show various radial overtones. The presence of multiple radial modes may allow us t…
Can turbulent convective variations drive the Blazhko cycle? Dynamical investigation of the Stothers idea
L. Molnár, Z. Kolláth, R. Szabó
The Blazhko-phenomenon, the modulation of the pulsation of RR Lyrae stars remains one of the most stubborn unsolved problems of stellar pulsation. The recent idea of Stothers propo…
Period doubling bifurcation and high-order resonances in RR Lyrae hydrodynamical models
Z. Kolláth, L. Molnár, R. Szabó
We investigated period doubling, a well-known phenomenon in dynamical systems, for the first time in RR Lyrae models. These studies provide theoretical background for the recent di…
Cepheid investigations using the Kepler space telescope
R. Szabó, L. Szabados, C. -C. Ngeow +35
We report results of initial work done on selected candidate Cepheids to be observed with the Kepler space telescope. Prior to the launch 40 candidates were selected from previous…
Flavours of variability: 29 RR Lyrae stars observed with Kepler
J. M. Benkő, K. Kolenberg, R. Szabó +18
We present our analysis of Kepler observations of 29 RR Lyrae stars, based on 138-d of observation. We report precise pulsation periods for all stars. Nine of these stars had incor…
Does Kepler unveil the mystery of the Blazhko effect? First detection of period doubling in Kepler Blazhko RR Lyrae stars
R. Szabó, Z. Kolláth, L. Molnár +15
The first detection of the period doubling phenomenon is reported in the Kepler RR Lyrae stars RR Lyr, V808 Cyg and V355 Lyr. Interestingly, all these pulsating stars show Blazhko…
First Kepler results on RR Lyrae stars
K. Kolenberg, R. Szabó, D. W. Kurtz +21
We present the first results of our analyses of selected RR Lyrae stars for which data have been obtained by the Kepler Mission. As expected, we find a significant fraction of the…
Multiple and changing cycles of active stars II. Results
K. Oláh, Z. Kolláth, T. Granzer +8
We study the time variations of the cycles of 20 active stars based on decades-long photometric or spectroscopic observations. A method of time-frequency analysis, as discussed in…