H. C. Spruit

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Use of the Hirsch-index (h) as measure of an author's visibility in the scientific literature has become popular as an alternative to a gross measure like total citations (c). I show that, at least in astrophysics, h correlates tightly with overall citations. The mean relation is h = 0.5(√ c + 1). Outliers are few and not too far from the mean, especially(More)
A grid of numerical simulations of double-diffusive convection is presented for the astrophysical case where viscosity (Prandtl number Pr) and solute diffusivity (Lewis number Le) are much smaller than the thermal diffusivity. As in laboratory and geophysical cases convection takes place in a layered form. The proper translation between subsonic flows in a(More)
A weakly magnetized (∼ 10 7 G) neutron star, slowly spun up by accretion in an X-ray binary, crosses the instability boundary for r-mode instability at P=1–2 msec. The amplitude of the oscillation, which initially increases only at the spinup time scale, is secularly unstable due to the negative temperature dependence of the viscosity in neutron star(More)
We investigate the effects of magnetic energy release by local magnetic dissipation processes in Poynting flux-powered GRBs. For typical GRB parameters (energy and baryon loading) the dissipation takes place mainly outside the photosphere, producing non-thermal radiation. This process converts the total burst energy into prompt radiation at an efficiency of(More)
The role of kink instability in magnetically driven jets is explored through numerical one-dimensional steady relativistic MHD calculations. The instability is shown to have enough time to grow and influence the dynamics of Poynting-flux dominated jets. In the case of AGN jets, the flow becomes kinetic flux dominated at distances > ∼ 1000rg because of the(More)