Radio maps of the Sun at λ = 1.95 cm     

Franca Chiuderi Drago  Marcello Felli 《Solar physics》1970,14(1):171-175

Two radio maps of the Sun at = 1.95 cm, taken at the N.R.A.O. (Green Bank) with a resolving power of 2.1 are studied and compared with H pictures: both bright and dark features appear to be strongly correlated. The emitted flux and the angular extent of the bright regions are given; from the observed radio-darkening of a region, the height of a prominence is derived.On leave from Osservatorio Astrofisico di Arcetri, Firenze.  相似文献   

Radio model of the transition layer in solar active regions     

Claudio Chiuderi  Franca Chiuderi Drago  Giancarlo Noci 《Solar physics》1971,17(2):369-378

A model of the transition layer of an active region of the Sun is presented based on radio observations. The model is deduced by using the Laplace transform of the brightness temperature and the hydrostatic equilibrium equation. A rational function, well-behaved in the coronal region, has been used to represent the observed brightness temperature. The model indicates the existence of a very steep temperature gradient and suggests the presence of a constant conductive flux from the corona into the chromosphere. Both these conclusions are quantitatively in a very good agreement with those deduced from the UV emission lines observations, thus removing a previous discrepancy between radio and optical based models. It is also shown that the presence of a weak magnetic field does not alter the above conclusions.  相似文献   

Magnetic fields and thermal structure of solar plasmas     

G. Einaudi  G. Torricelli-Ciamponi  C. Chiuderi 《Solar physics》1984,92(1-2):99-107

The connection between the magnetic field geometry and the thermal properties of solar coronal structures is investigated. Gravitational effects, that can modify the spatial dependence of the thermodynamical quantities, but have no influence on the plasma-field interaction, are omitted to simplify the problem. A series of two-dimensional models is constructed, in which a strong coupling between the magnetic field shear and the thermal structure of the loop is clearly pointed out.It is shown how it is possible to deduce detailed information on the small scale magnetic structure by the use of measurement of purely thermodynamical quantities. Similarly information on the spatial dependence of the energy deposition function can also be obtained.  相似文献   

The filament-corona transition region from OSO-VI EUV observations     

Franca Chiuderi Drago  Maurizio Silvi 《Solar physics》1977,55(1):177-180

The transition region between filament and corona is investigated measuring the intensity of six EUV lines above two filaments on the disk observed on September 1 and 2, 1969 by OSO-VI. The comparison between these intensities and those observed on quiet regions shows that there is no difference between the two transition regions.  相似文献   

Joint EUV/Radio Observations of a Solar Filament     

Chiuderi Drago  F.  Alissandrakis  C.E.  Bastian  T.  Bocchialini  K.  Harrison  R.A. 《Solar physics》2001,199(1):115-132

In this paper we compare simultaneous extreme ultraviolet (EUV) line intensity and microwave observations of a filament on the disk. The EUV line intensities were observed by the CDS and SUMER instruments on board SOHO and the radio data by the Very Large Array and the Nobeyama radioheliograph. The main results of this study are the following: (1) The Lyman continuum absorption is responsible for the lower intensity observed above the filament in the EUV lines formed in the transition region (TR) at short wavelengths. In the TR lines at long wavelengths the filament is not visible. This indicates that the proper emission of the TR at the filament top is negligible. (2) The lower intensity of coronal lines and at radio wave lengths is due to the lack of coronal emission: the radio data supply the height of the prominence, while EUV coronal lines supply the missing hot matter emission measure (EM). (3) Our observations support a prominence model of cool threads embedded in the hot coronal plasma, with a sheath-like TR around them. From the missing EM we deduce the TR thickness and from the neutral hydrogen column density, derived from the Lyman continuum and Hei absorption, we estimate the hydrogen density in the cool threads.  相似文献