Related papers: The triple-mode pulsating variable V823 Cas
The quasi-periodic oscillations (QPOs) observed in the tails of magnetar giant $\gamma$-ray flares have long been interpreted as normal oscillation modes of these stars. However, most studies modelling QPOs have neglected some key features…
The present work explores the theoretical effects of rotation in calculating the period ratios of double-mode radial pulsating stars with special emphasis on high-amplitude delta Scuti stars (HADS). Diagrams showing these period ratios vs.…
The $\gamma$-ray emitting binary LS I +61 303 exhibits periodic emission across the electromagnetic spectrum, from radio up to the very-high-energy regime. The most prominent features are the three periods $P_1 = 26.5$ d, $P_2 = 26.9$ d,…
Arecibo observations of the conal triple pulsar B1918+19 at 0.327- and 1.4-GHz are used to analyse its subpulse behaviour in detail. We confirm the presence of three distinct drift modes (A,B,C) plus a disordered mode (N) and show that they…
Radio pulsars exhibit an enormous diversity of single pulse behaviour that involves sudden changes in pulsation mode and nulling occurring on timescales of tens or hundreds of spin periods. The pulsations appear both chaotic and…
Photometric observations from the last decade have revealed additional low-amplitude periodicities in many classical pulsators that are likely due to pulsations in non-radial modes. One group of multi-mode RR Lyrae stars, the so-called 0.61…
The resonance frequencies and oscillation phases of three acoustically coupled bubbles are examined to show that avoided crossings can appear in a multibubble system. Via a simple coupled oscillator model, we show that if at least three…
An understanding of pulsar timing noise offers the potential to improve the timing precision of a large number of pulsars as well as facilitating our understanding of pulsar magnetospheres. For some sources, timing noise is attributable to…
We explore the tidal excitation of stellar modes in binary systems using Kepler observations of the remarkable eccentric binary KOI-54 (HD 187091; KIC 8112039), which displays strong ellipsoidal variation as well as a variety of linear and…
Accreting X-ray pulsars (XRPs) undergo different physical regimes depending on the mass accretion rate. Recent observations have shown a dramatic change in the emission properties of this class of sources observed at low luminosity. We…
The emission geometries, e.g. the emission region height, the beam shape, and radius-to-frequency mapping, are important predictions of pulsar radiation model. The multi-band radio observations carry such valuable information. In this…
We present the frequency analysis of the multicolour time series photometry of the field RRd variable BS Comae. The large number of data points in each of the BV(RI)_c bands and the ~0.01 magnitude accuracy of the individual measurements…
Waves scattered at a self-oscillating mode can exhibit superradiance, or net amplification of an external harmonic excitation. This exotic behavior, arising from the nonlinear coupling between the mode and the incident wave, is…
Multiplet structures are a common feature in pulsating stars, and can be the consequence of rotational splitting, mode interaction or sinusoidal amplitude variations. In this paper we examine the phenomenon of (nearly) equidistant triplets,…
We have investigated the Quasi Periodic Oscillation (QPO) properties of the transient accreting X-ray pulsar XTE J1858+034 during the second outburst of this source in April-May 2004. We have used observations made with the Proportional…
Magnetohydrodynamic instabilities like Toroidal Alfv\'en Eigenmodes or core-localized modes such as Beta Induced Alfv\'en Eigenmodes and Reversed Shear Alfv\'en Eigenmodes driven by fast particles can lead to significant redistribution and…
PSR B0031-07 is well known to exhibit three different modes of drifting sub-pulses (mode A, B and C). It has recently been shown that in a multifrequency observation, consisting of 2700 pulses, all driftmodes were visible at low…
We present an analysis of the emission behaviour of PSR J1107-5907, a source known to exhibit separate modes of emission, using observations obtained over approximately 10 yr. We find that the object exhibits two distinct modes of emission;…
Femtosecond time-resolved x-ray diffraction is employed to study the dynamics of the periodic lattice distortion (PLD) associated with the charge-density-wave (CDW) in K0.3MoO3. Using a multi-pulse scheme we show the ability to extend the…
The detection of pulsations from an X-ray binary is an unambiguous signature of the presence of a neutron star in the system. When the pulsations are missed in the radio band, their detection at other wavelengths, like X-ray or gamma-rays,…