Aims. We report the detection of a magnetic field on Vega through spectropolarimetric observations. Methods. We acquired 257 Stokes V high signal-to-noise and high-resolution echelle spectra during four consecutive nights with NARVAL spectropolarimeter at the 2-m Telescope Bernard Lyot of Observatoire du Pic du Midi (France). A circularly polarized signal in line profiles is detected after gath...

A new-developed 3D numerical code is applied to an uniform external (primordial) magnetic field subject to a complex flow pattern representing the situation in a turbulent spiral galaxy.The spiral arms are definedby the radial-azimuthal profiles of density and the turbulent velocity, but they do not yet possess any own large-scale velocity field. No dynamo alpha is assumed to exist, but all the...

We employ a fireball model of the gamma-ray burst explosion to constrain intrinsic and environmental parameters of four events with good broadband afterglow data; GRB 970508, GRB 980329, GRB 980703, and GRB 000926. Using the standard assumptions of constant circumburst density and no evolution of the fraction of the explosion energy in the post-shock magnetic field, we investigate the uniformit...

In this work, high-beta plasma effects are investigated in a low-pressure helicon plasma source attached to a large volume diffusion chamber. When operating above an input power of 900 W and a magnetic field of 30 G a narrow column of bright blue light due to Ar II radiation is observed along the axis of the diffusion chamber. With this blue mode, the plasma density is axially very uniform in t...

The current trend for Magnetic Resonance Imaging points towards higher magnetic fields. Even though sensitivity and resolution are increased in stronger fields, T1 contrast is often reduced, and this represents a challenge for contrast agent design. Field-dependent measurements of relaxivity are thus important to characterize contrast agents. At present, the field-dependent curves of relaxivity...

In this study the effect of magnetic Reynolds number variation on magnetic distribution of natural convection heat transfer in an enclosure is numerically investigated. The geometry is a two dimensional enclosure which the left wall is hot, the right wall is cold and the top and bottom walls are adiabatic. Fluid is molten sodium with Pr=0.01 and natural convection heat transfer for Rayleigh num...

The ion saturation current to a spherical probe in the entire range of ion magnetization is computed with SCEPTIC3D, new three-dimensional version of the kinetic code SCEPTIC designed to study transverse plasma flows. Results are compared with prior two-dimensional calculations valid in the magnetic-free regime [I.H. Hutchinson PPCF 44:1953 (2002)], and with recent semi-analytic solutions to th...

We present the first simultaneous infrared (IR) and visible spectro-polarimetric observations of a solar internetwork region. The Fe I lines at λ6301.5 Å, λ6302.5 Å, λ15648 Å, and λ15652 Å were observed, with a lag of only 1 min, using highly sensitive spectro-polarimeters operated in two different telescopes (VTT and THEMIS at the Observatorio del Teide). Some 30% of the observed region shows ...

The ion saturation current to a spherical probe in the entire range of ion magnetization is computed with SCEPTIC3D, new three-dimensional version of the kinetic code SCEPTIC designed to study transverse plasma flows. Results are compared with prior two-dimensional calculations valid in the magnetic-free regime [I.H. Hutchinson, PPCF 44:1953 (2002)], and with recent semi-analytic solutions to t...

We consider the effect of a random magnetic field in the convective zone of the Sun on resonant neutrino spin-flavour oscillations. The expected signals in the different experiments (SK,GALLEX-SAGE,Homestake) are obtained as a function of the level of noise, regular magnetic field and neutrino mixing parameters. Previous results obtained for small mixing and ad-hoc regular magnetic profiles are...