The active region, AR0554, was observed with NIS/CDS on board SoHO to examine the extent and range of oscillations from a range of features. Among all the NIS spectral lines analysed, significant oscillations were found in Si xii 520 Å, Mg x 625 Å, O v 629 Å, and He i 522 Å. The periods of the strongest oscillations in these lines were ≈ 10–20 min. After the dominant 10–20 min oscillations were...

Introduction Conclusions References Tables Figures ◭ ◮ ◭ ◮ Back Close Full Screen / Esc Abstract Introduction Conclusions References Tables Figures ◭ ◮ ◭ ◮ Back Close Full Screen / Esc Printer-friendly Version Interactive Discussion EGU Abstract A solar eclipse is a rare but spectacular natural phenomenon and furthermore it is a challenge for radiative transfer modeling. Whereas a simple one-di...

The conjecture that energy transport in sunspot penumbrae occurs through convection by an interchange of magnetic flux tubes is used in order to construct a magnetostatic model for a deep penumbra which is part of a global sunspot model. The model describes an overall mechanical equilibrium between the three stratifications: of the umbra, the penumbra, and of the solar convection zone, all of t...

The presence of fine structures in the sunspot vector magnetic fields has been confirmed from Hinode as well as other earlier observations. We studied 43 sunspots based on the data sets taken from ASP/DLSP, Hinode (SOT/SP) and SVM (USO). In this Letter, (i) We introduce the concept of signed shear angle (SSA) for sunspots and establish its importance for non force-free fields. (ii) We find that...

The brightness temperature of the radio free–free emission at millimeter range is an effective tool for characterizing the vertical structure of the solar chromosphere. In this paper, we report on the first single-dish observation of a sunspot at 85 and 115 GHz with sufficient spatial resolution for resolving the sunspot umbra using the Nobeyama 45 m telescope. We used radio attenuation materia...

The reference links to the modern " classical umbral calculus " (before that properly called Blissard's symbolic method) and to Steffensen-actuarialist.....are numerous. The reference links to the EFOC (Extended Finite Operator Calculus) founded by Rota with numerous outstanding Coworkers, Followers and Others ... and links to Roman-Rota functional formulation of umbra calculi ... .....are gian...

The low ionization state in parts of a sunspot may play an important role in its evolution and dynamical state. The cool magnetic interior region of the sunspot develops a substantial neutral atomic and molecular hydrogen osmotic pressure which can drive a wind outward from the umbra. Ambipolar diffusion against the magnetically pinned ionized plasma component can also distort the umbral magnet...

Prel iminary results of tbe measurements of the electroQ and ion components of plasma obtained by means of wide-angle detectors onboard the Venera-9 and Venera-l0 satell ites are presented. Stable electron and fluctuating ion fluxes were detected in the optical and corpuscular umbra. As a result of the plasma characteristics ob­ served at a few hundred kilometers above the optical umbra, we ref...