Context: We present observations of the GRB 080319B afterglow at optical, mm, and radio frequencies between a few hours and 67 days after the burst. Aims: We attempt to understand the nature of this extraordinarily bright explosion based on the observed properties and its comparison with afterglow models. Methods: Our observations and other

Energy transport by radiation is an important contribution to the energy budget in stellar atmospheric structures. In this paper, radiative relaxation of small-scale structures is investigated. The authors show in a linear analysis: (1) Already at structural lengths of 10 opacity scale heights, horizontal photon exchange is important for the energy

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Combining observations of spectral lines with different Zeeman sensitivities, it is possible to infer some properties of the small-scale solar magnetic fields. This paper presents a theoretical analysis of the diagnostics potential of 14 different spectral lines when used for this purpose. These lines span a broad range of wavelengths from the

Context: To obtain a significant Zeeman signature in the polarised spectra of a magnetic star, we usually “add” the contributions of numerous spectral lines; the ultimate goal is to recover the spectropolarimetric prints of the magnetic field in these line additions. Aims: Here we want to clarify the meaning of these techniques of line addition; in

On the basis of a large amount of high-precision photoelectric photometric data obtained at three sites and by use of the method of Fourier period analysis, the multiple frequencies of HD 213534 have been obtained. Five frequencies have been definitely detected. After an analysis of the star's pulsation modes, it is concluded that it is a multiple