With the aim of studying magnetic effects in time-distance helioseismology, we use the first-order Born approximation to compute the scattering of acoustic plane waves by a magnetic cylinder embedded in a uniform medium. We show, by comparison with the exact solution, that the travel-time shifts computed in the Born approximation are everywhere valid to first order in the ratio of the magnetic to the gas pressures. We also show that, for arbitrary magnetic field strength, the Born approximation is not valid in the limit where the radius of the magnetic cylinder tends to zero.

We review here recent numerical results concerning the acceleration and collimation of relativistic outflows from neutron stars, and we discuss their implications for models of magnetars in their hypothesized initial high rotation states. New results with different injection conditions and extending to much larger distance from the central star are also presented and discussed, showing that, only in the case of weakly magnetized winds, collimated outflows are indeed possible. We finally comment on the possibility that newly born magnetars might trigger GRBs, and we show that numerical results do not support such hypothesis.

We have added the BeppoSAX Gamma-Ray Burst Monitor to the 3rd Interplanetary Network of burst detectors. We analyze 16 bursts whose positions are known to good accuracy from measurements at other wavelengths. We show that there is excellent agreement between the Ulysses/BeppoSAX triangulation annuli and the known positions of these events, and that these annuli can in many cases provide useful constraints on the positions of bursts detected by the BeppoSAX Wide Field Camera and Narrow Field Instruments.