A principal candidate for quiescent non-thermal gamma-ray emission from magnetars is resonant inverse Compton scattering in the strong fields of their magnetospheres. This paper outlines expectations for such emission, formed from non-thermal electrons accelerated in a pulsar-like polar cap potential upscattering thermal X-rays from the hot stellar surface. The resultant spectra are found to be...

Context. The identification of pulsation modes in δ Scuti stars is mandatory to constrain the theoretical stellar models. The non-adiabatic observables used in the photometric identification methods depend, however, on convection modeling in the external layers. Aims. To determine how the treatment of convection in the atmospheric and sub-atmospheric layers affects the mode identification, and ...

The discovery of β Cephei stars in low metallicity environments, as well as the difficulty in theoretically explaining the excitation of the pulsation modes observed in some β Cephei and hybrid SPB-β Cephei pulsators, suggest that the “iron opacity bump” provided by stellar models could be underestimated. We analyze the effect of uncertainties in the opacity computations and in the solar metal ...

A new time-series analysis of profile changes in the photospheric He I λ4713 spectral line from data taken during 5 days in 1989 at the Calar Alto and Kitt Peak observatories has provided evidence for the presence of a non-radial prograde p-mode in the O 7.5 giant ξ Per (` = 3, P = 3.5) and probably two such modes in the O6 supergiant λ Cep (` = 3, P = 12.3 h and ` = 5, P = 6.6 h). The corotati...

We present the results of non-linear pulsation modelling of 20 bump Cepheids in the LMC. By obtaining a optimal fit to the observed V, R MACHO lightcurves we have placed tight constraints on stellar parameters of M , L, Teff and well as quantities of distance modulus and reddening. We describe the mass-luminosity relation for core-He burning for intermediate mass stars. The mass-luminosity rela...

Data on multimode Cepheids from OGLE-III catalog of the LMC Cepheids are confronted with results from model calculations. Models whose radial mode periods are consistent with observation are not always in agreement with published evolutionary models. Nonradial mode interpretation is considered for the cases of unusual period ratios. The greatest challenge for stellar pulsation theory is explana...

We describe an implicit 1–D adaptive mesh hydrodynamics code that is specially tailored for radial stellar pulsations. In the Lagrangian limit the code reduces to the well tested Fraley scheme. The code has the useful feature that unwanted, long lasting transients can be avoided by smoothly switching on the adaptive mesh features starting from the Lagrangean code. Thus, a limit cycle pulsation ...

Two kinds of pre-white dwarf stars can be probed through asteroseismology: planetary nebula nuclei (PNNs) and sdB (EHB) stars. To exploit the observed pulsations requires models that incorporate state-ofthe-art input physics and realistic evolutionary histories. Pulsation analysis of extensive grids of such models provide self-consistent theoretical pulsation periods for comparison with observe...