Related papers: The Onset of Chaos in Pulsating Variable Stars
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…
M giants are among the longest-period pulsating stars which is why their studies were traditionally restricted to analyses of low-precision visual observations, and more recently, accurate ground-based data. Here we present an overview of M…
Pulsar glitches are thought to be probes of the superfluid interior of neutron stars. These sudden jumps in frequency observed in many pulsars are generally assumed to be the macroscopic manifestation of superfluid vortex motion on a…
We have performed a linear pulsational stability survey of 6 series of long period variable models with M=1.0 Msun, L=3000 - 8000Lsun, and (X,Z)= (0.700,0.020),(0.735,0.005). The dynamic and thermodynamic couplings between convection and…
Many pulsars exhibit a peculiar behaviour in their pulse profile of a sudden increase in their rotational period, which is popularly known as a pulsar glitch. Some of them show giant glitches with relative amplitude $\Delta\Omega/\Omega…
New high-cadence observations with BRITE covering many months confirm that coupled pairs of nonradial pulsation modes are widespread among early-type Be stars. With the difference frequency between the parental variations they may form a…
High-precision photometric observations have revealed ubiquitous stochastic low-frequency photometric variability in early type stars. It has been suggested that this variability arises due to either subsurface convection or internal…
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…
Aims. We aim to study chemically peculiar Am and Fm stars, distinguished by their unique abundance patterns, which are crucial for studying mixing processes in intermediate-mass stars. These stars provide a window into the atomic diffusion…
We discuss visual observations spanning nearly 70 years of the nearby semiregular variable R Doradus. Using wavelet analysis, we show that the star switches back and forth between two pulsation modes having periods of 332 days and about 175…
Perturbations of rotating relativistic stars can be classified by their behavior under parity. For axial perturbations (r-modes), initial data with negative canonical energy is found with angular dependence $e^{im\phi}$ for all values of…
The long-term evolution of the relative rotation of the core superfluid in a neutron star with respect to the rest of the star, at different radial distances from the rotation axis, is determined through model calculations. The core…
As a result of resonance overlap, planetary systems can exhibit chaotic motion. Planetary chaos has been studied extensively in the Hamiltonian framework, however, the presence of chaotic motion in systems where dissipative effects are…
Neutron stars or pulsars are very rapidly rotating compact stars with extremely high density. One of the unsolved long-standing problems of these enigmatic celestial bodies is the origin of pulsars' glitches, i.e., the sudden rapid…
We obtained a series of more than two hundred R-band CCD images for the crowded central (115"x77") region of the metal-poor globular cluster M15 with an angular resolution of 0.5"-0.9" in most images. Optimal image subtraction was used to…
Space photometry has revealed rich pulsation spectra in classical Be stars. Often frequency pairs can be found that differ by nearly the frequency of a third genuine stellar variability. The lowest currently known of these so-called…
Polaris is one of the most observed stars in the night sky, with recorded observations spanning more than 200 years. From these observations, one can study the real-time evolution of Polaris via the secular rate of change of the pulsation…
We present estimates of the amplitudes of intrinsically stable stochastically excited radial oscillations in stars near the main sequence. The amplitudes are determined by the balance between acoustical energy generation by turbulent…
Pulsations in RR Lyrae stars and classical Cepheids were thought to be relatively simple since they typically pulsate only in one or two radial modes. This picture changes at a closer look when modulation or additional low-amplitude signals…
Theoretical estimates of the pulsation period change rates in LMC Cepheids are obtained from consistent calculation of stellar evolution and nonlinear stellar pulsation for stars with initial chemical composition X=0.7, Z=0.008, initial…