Related papers: Strange nonchaotic stars
Recent progress in the studies of pulsating variable stars is summarized from an observational point of view. A number of unexpected phenomena have been revealed in the case of pulsators in the classical instability strip. These discoveries…
The oscillation spectrum of pressure waves in stars can be determined by monitoring their luminosity. For rapidly rotating stars, the corresponding ray dynamics is mixed, with chaotic and regular zones in phase space. Our numerical…
The observed scarcity of chaotic phenomena in astronomy contrasts sharply with their theoretical significance, primarily due to the absence of a robust framework for detecting chaos. In this study, we numerically simulate the light curves…
Pulsational variability is observed in several types of main sequence stars with anomalous chemical abundances. In this contribution I summarize the relationship between pulsations and chemical peculiarities, giving special emphasis to…
Peculiar A stars are so named because they exhibit abundance peculiarities in their atmospheres. It is believed that these arise as a result of differentiation of chemical species in large magnetic spots in which convective mixing is…
The Kepler spacecraft is providing photometric time series with micro-magnitude precision for thousands of variable stars. The continuous time-series of unprecedented time span open up opportunities to study the pulsational variability in…
The {\delta} Sct stars are a diverse group of intermediate-mass pulsating stars located on and near the main sequence within the classical instability strip in the Hertzsprung-Russell diagram. Many of these stars are hybrid stars pulsating…
In this paper we discuss four early F-type variable stars whose periods are an order of magnitude slower than known pulsators of comparable luminosity. They cannot be stars undergoing simple radial pulsations. For one or more of these stars…
We present Kepler light curves and optical spectroscopy of twenty X-ray bright stars located in the Kepler field of view. The stars, spectral type FK, show evidence for rapid rotation including chromospheric activity 100 times or more above…
In this lecture, we give a first introduction to neutron stars, based on fundamental physical principles. After outlining their amazing macroscopic properties, as obtained from observations, we infer the extreme conditions of matter in…
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 of low-amplitude pulsation modes that were undetectable…
Anomalous redshifts of some galactic objects such as binary stars, early-type stars in the solar neighborhood, and O stars in a star clusters are discussed. It is shown that all these phenomena have a common characteristic, that is, the…
The Kepler mission provides an exciting opportunity to study the lightcurves of stars with unprecedented precision and continuity of coverage. This is the first look at a large sample of stars with photometric data of a quality that has…
Continuous and discrete time systems possessing strange non-chaotic attractors are under investigation. It is demonstrated that unpredictable trajectories exist in the dynamics. A recent numerical technique, the sequential test, is utilized…
The properties of radial nonlinear pulsations of massive blue stars are computed with the MESA software instrument in its dynamical mode. Pulsational instabilities could be computationally detected and followed if the evolutionary timestep…
Pulsational properties of 1.8 M$_{\odot}$ stellar models covering the latest stages of contraction toward the main sequence up to early hydrogen burning phases are investigated by means of linear nonadiabatic analyses. Results confirm that…
We present the results of time-series photometric analysis of 15106 A-K type stars observed by the Kepler space mission. We identified 513 new rotational variables and measured their starspot rotation periods as a function of spectral type…
In this talk, after briefly reviewing some historical remarks concerning strange stars, the achievements in physics and dynamical behavior of strange stars are discussed. Especially, various observational effects in distinguishing strange…
The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds of A-F type stars. We present a first general characterization of the pulsational behaviour of A-F type stars as observed in the…
In the course of their evolution, white-dwarf stars go through at least one phase of variability in which the global pulsations they undergo allow astronomers to peer into their interiors, this way making possible to shed light on their…