Communications in Asteroseismology

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ISSN / EISSN : 1021-2043 / 1021-2043
Total articles ≅ 388
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Peter Reegen
Communications in Asteroseismology, Volume 163, pp 99-131; https://doi.org/10.1553/cia163s99

Abstract:
Cinderella is a software solution for the quantitative comparison of time series in the frequency domain. It assigns probabilities to coincident peaks in the DFT amplidude spectra of the datasets under consideration. Two different modes are available. In conditional mode, Cinderella examines target and comparison datasets on the assumption that the latter contain artifacts only, returning the conditional probability of a target signal, although there is a coincident signal in the comparison data within the frequency resolution. In composed mode, the probability of coincident signal components in both target and comparison data is evaluated. Cinderella permits to examine multiple target and comparison datasets at once.
Peter Reegen
Communications in Asteroseismology, Volume 163, pp 3-98; https://doi.org/10.1553/cia163s3

Abstract:
SigSpec computes the spectral significance levels for the DFT (Discrete Fourier Transform) amplitude spectrum of a time series at arbitrarily given sampling. It is based on the analytical solution for the Probability Density Function (PDF) of an amplitude level, including dependencies on frequency and phase and referring to white noise. Using a time series dataset as input, an iterative procedure including step-by-step prewhitening of the most significant signal components and MultiSine leastsquares fitting is provided to determine a whole set of signal components, which makes the program a powerful tool for multi-frequency analysis. Instead of the step-by-step prewhitening of the most significant peaks, the program is also able to take into account several steps of the prewhitening sequence simultaneously and check for the combination associated to a minimum residual scatter. This option is designed to overcome the aliasing problem caused by periodic time gaps in the dataset. SigSpec can detect non-sinusoidal periodicities in a dataset by simultaneously taking into account a fundamental frequency plus a set of harmonics. Time-resolved spectral significance analysis using a set of intervals of the time series is supported to investigate the development of eigenfrequencies over the observation time. Furthermore, an extension is available to perform the SigSpec analysis for multiple time series input files at once. In this MultiFile mode, time series may be tagged as target and comparison data. Based on this selection, SigSpec is capable of determining differential significance spectra for the target datasets with respect to coincidences in the comparison spectra. A built-in simulator to generate and superpose a variety of sinusoids and trends as well as different types of noise completes the software package at the present stage of development.
Michael Breger
Communications in Asteroseismology, Volume 163; https://doi.org/10.1553/cia163si

Abstract:
Die Serie Communications in Asteroseismology (CoAst) stellt eine international gefragte Plattform für wissenschaftliche Publikationen der neuesten Forschungsergebnisse auf dem Gebiet der Asteroseismologie dar. Forschungsgegenstand der Asteroseismologie sind veränderliche und pulsierende Sterne. Neben den halbjährlich erscheinenden regulären Ausgaben mit Beiträgen aus der laufenden Forschung werden auch Sonderausgaben für Konferenzberichte bzw. Programmhandbücher herausgegeben. Contents: SigSpec User's Manual by P. Reegen Cinderella User's Manual by P. Reegen
Michael Breger
Communications in Asteroseismology, Volume 163; https://doi.org/10.1553/cia163siii

Abstract:
Die Serie Communications in Asteroseismology (CoAst) stellt eine international gefragte Plattform für wissenschaftliche Publikationen der neuesten Forschungsergebnisse auf dem Gebiet der Asteroseismologie dar. Forschungsgegenstand der Asteroseismologie sind veränderliche und pulsierende Sterne. Neben den halbjährlich erscheinenden regulären Ausgaben mit Beiträgen aus der laufenden Forschung werden auch Sonderausgaben für Konferenzberichte bzw. Programmhandbücher herausgegeben. Contents: SigSpec User's Manual by P. Reegen Cinderella User's Manual by P. Reegen
Jeffrey D. Scargle
Communications in Asteroseismology, Volume 163, pp 1-2; https://doi.org/10.1553/cia163s1

Abstract:
Die Serie Communications in Asteroseismology (CoAst) stellt eine international gefragte Plattform für wissenschaftliche Publikationen der neuesten Forschungsergebnisse auf dem Gebiet der Asteroseismologie dar. Forschungsgegenstand der Asteroseismologie sind veränderliche und pulsierende Sterne. Neben den halbjährlich erscheinenden regulären Ausgaben mit Beiträgen aus der laufenden Forschung werden auch Sonderausgaben für Konferenzberichte bzw. Programmhandbücher herausgegeben. Contents: SigSpec User's Manual by P. Reegen Cinderella User's Manual by P. Reegen
Isolde Müller
Communications in Asteroseismology, Volume 162, pp 1-6; https://doi.org/10.1553/cia162s1

Abstract:
Die Serie Communications in Asteroseismology (CoAst) stellt eine international gefragte Plattform für wissenschaftliche Publikationen der neuesten Forschungsergebnisse auf dem Gebiet der Asteroseismologie dar. Forschungsgegenstand der Asteroseismologie sind veränderliche und pulsierende Sterne. Neben den halbjährlich erscheinenden regulären Ausgaben mit Beiträgen aus der laufenden Forschung werden auch Sonderausgaben für Konferenzberichte bzw. Programmhandbücher herausgegeben. Contents Analyses of Crawford’s uvby ß calibrations using the pulsational variations of FG Vir by P.Haas A spectroscopic study of the hybrid pulsator γ Pegasi by C. P. Pandey, T.Morel, M. Briquet, et al. Frequency analysis of five short periodic pulsators by A. Liakos, P.Niarchos Update and Additional Frequencies for Kepler Star KIC 970032 by Joyce A. Guzik, Michel Breger New pulsation analysis of the oscillating Eclipsing Binary BG Peg by A. Liakos, P.Niarchos
C.P. Pandey, T. Morel, M. Briquet, S. Bisht, B.B. Sanwal
Communications in Asteroseismology, Volume 162, pp 21-50; https://doi.org/10.1553/cia162s21

Abstract:
The recent detection of both pressure and high-order gravity modes in the classical B-type pulsator Pegasi offers promising prospects for probing its internal structure through seismic studies. To aid further modelling of this star, we present the results of a detailed NLTE abundance analysis based on a large number of time-resolved, high-quality spectra. A chemical composition typical of nearby B-type stars is found. The hybrid nature of this star is consistent with its location in the overlapping region of the instability strips for ß Cephei and slowly pulsating B stars computed using OP opacity tables, although OPAL calculations may also be compatible with the observations once the uncertainties in the stellar parameters and the current limitations of the stability calculations are taken into account. The two known frequencies f1 = 6.58974 and f2 = 0.68241 d-1 are detected in the spectroscopic time series. A mode identification is attempted for the low-frequency signal, which can be associated to a high-order g-mode. Finally, we re-assess the binary status of γ Peg and find no evidence for variations that can be ascribed to orbital motion, contrary to previous claims in the literature.
, P. Niarchos
Communications in Asteroseismology, Volume 162, pp 51-61; https://doi.org/10.1553/cia162s51

Abstract:
CCD observations of five newly discovered pulsating stars are analyzed using the Period04 software for a comprehensive investigation of their pulsation properties. The type of their variability is discussed, and the pulsation frequencies and Fourier spectra are presented.
, P. Niarchos
Communications in Asteroseismology, Volume 162, pp 73-80; https://doi.org/10.1553/cia162s73

Abstract:
New BVRI light curves of the eclipsing binary BG Peg were obtained and analysed using the Wilson-Devinney code. The observations (102 hours during a span of 108 days) were collected to perform an accurate frequency analysis of the pulsations of the primary component of the system, which is of δ Sct type. Three pulsation frequencies were identified in that star.
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