A new iterative method for solving non-LTE multilevel radiative transfer (RT) problems in 1D, 2D or 3D geometries is presented. The scheme obtains the self-consistent solution of the kinetic and RT equations at the cost of only a few (

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Cyg OB2 No. 5 (BD+40deg4220; V729 Cyg) is known to be a contact binary system formed by two O-type stars. For this object a 6-cm radio emission has been detected at the optical position as well as an additional weak non-thermal radio source located at ~ 0.9 arcsec to the north east of the contact binary. It has been suggested that this radio

IAUC 6721 available at Central Bureau for Astronomical Telegrams.

A new method of fitting tridimensional power spectra of solar oscillations is described and compared with a previous one whose use has been more common. The new method fits the parameters of the Lorentzian profiles in a bidimensional k - omega diagram constructed from an azimuthal average of the tridimensional one. The horizontal velocities are

Photospheric and chromospheric solar magnetograms sometimes show opposite polarity. This intriguing phenomenon is associated with the emergence of magnetic flux and with nearby, but not necessarily superposed, flaring activity. Despite the fact that there may be different explanations, it is shown here that the observed reversals are consistent