Related papers: Longitudinal drift of Tayler instability eigenmode…
The quasiperiodic oscillations found in the three giant flares of soft gamma-ray repeaters observed to date have been interpreted as crustal oscillations caused by a starquake following a dramatic rearrangement of the stellar magnetic…
We investigate the evolution of a thin viscous disc surrounding magnetic star, including the spindown of the star by the magnetic torques it exerts on the disc. The transition from an accreting to a non-accreting state, and the change of…
We present analytical and numerical studies of magnetorotational instabilities occuring in magnetized accretion disks. In these studies we make use of the linearised compressible MHD equations. These calculations are performed for general…
Acceleration of ultrathin plasma foils by laser radiation pressure promises compact alternatives to the conventional ion accelerators. It was shown, that a major showstopper for such schemes is a strong transverse instability, which…
Apparent variability of the longitudinal magnetic fields in most stars is caused by rotation, which quantitavely changes projection of the magnetic field configuration on the line of sight. This is a purely geometrical effect and is not…
This work presents a global solution for the internal and the external field of an axisymmetric rotating neutron star. It is shown that the twist of the internal field affects the external field, by increasing the number of open field lines…
The question is addressed whether stellar differentially rotating radiative zones (like the solar tachocline) excite nonaxisymmetric r-modes which can be observed. To this end the hydrodynamical stability of latitudinal differential…
Asteroseismology has revealed small core-to-surface rotation contrasts in stars in the whole HR diagram. This is the signature of strong transport of angular momentum (AM) in stellar interiors. One of the plausible candidates to efficiently…
The strong magnetic fields of neutron stars are closely linked to their observed thermal, spectral, and timing properties, such as the distribution of spin periods and their derivatives. To understand the evolution of astrophysical…
We investigate the 50-year old hypothesis that the magnetic fields of the Ap stars are stable equilibria that have survived in these stars since their formation. With numerical simulations we find that stable magnetic field configurations…
The atmosphere of a hot jupiter may be subject to a thermo-resistive instability, in which the increasing electrical conductivity with temperature leads to runaway Ohmic heating. We introduce a simplified model of the local dynamics in the…
Magnetic buoyancy instability plays an important role in the evolution of astrophysical magnetic fields. Here we revisit the problem introduced by \citet{Gilman_1970} of the short wavelength linear stability of a plane layer of compressible…
The nature of the 5-12 s "anomalous" X-ray pulsars remains a mystery. Among the models that have been proposed to explain the properties of AXPs, the most likely ones are: (1) isolated accreting neutron stars evolved from the…
We investigate the photometric variability of magnetized stars, particularly neutron stars, accreting through a magnetic Rayleigh-Taylor-type instability at the disk-magnetosphere interface, and compare it with the variability during stable…
The angular momentum (AM) content of massive stellar cores helps to determine the natal spin rates of neutron stars and black holes. Asteroseismic measurements of low-mass stars have proven that stellar cores rotate slower than predicted by…
We study the magnetosphere of a slowly rotating magnetized neutron star subject to toroidal oscillations in the relativistic regime. Under the assumption of a zero inclination angle between the magnetic moment and the angular momentum of…
Rotation plays a key role in stellar structure and its evolution. Through transport processes which induce rotational mixing of chemical species and the redistribution of angular momentum, internal stellar rotation influences the…
Rapidly rotating giant stars are relatively rare and may represent important stages of stellar evolution, resulting from stellar coalescence of close binary systems or accretion of sub-stellar companions by their hosting stars. In the…
We present a case study for the relevance of the r-mode instability for accreting compact stars. Our estimates are based on approximations that facilitate back-of-the-envelope calculations. We discuss two different cases: 1) For recycled…
Exact models of uniformly rotating strange stars, built of self bound quark matter, are calculated within the framework of general relativity. This is made possible thanks to a new numerical technique capable to handle the strong density…