Results 251 to 260 of about 355,664 (292)

Infrared Photometry of Solar Active Regions

International Astronomical Union Colloquium, 2000
AbstractSimultaneous time series of broad-band images of two active regions close to the disk center were acquired at the maximum (0.80μm) and minimum (1.55μm) continuum opacities. Dark faculae are detected in images obtained as weighted intensity differences between both wavelength bands. The elements of quiet regions can be clearly distinguished from
M. Sobotka, M. Vázquez, M. Sánchez Cuberes, J. A. Bonet, A. Hanslmeier   +4 more
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Active Region Evolution and Solar Flux Variations

Solar Physics, 1994
The goal of this study is to relate the changes in the solar radiative output to the growth and decay of magnetic active regions. We will test the assumption that each index of radiation variability is a convolution of an active-region magnetic driving function and a response function.
T. P. Hartsell, P. L. Bornmann
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Abundance determination in solar active region

Advances in Space Research, 1994
An improved method has been developed to evaluate element abundances from emission line intensities of thin plasmas, depending on the differential emission measure (DEM) of the source. Observations made by the Solar EUV Rocket Telescope and Spectrograph (SERTS) Rocket EUV Spectrograph are used to perform a detailed analysis of the DEM distribution for ...
B.C.Monsignori Fossi, M. Landini, R.J. Thomas, W.M. Neupert   +3 more
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Oscillations of Ellipsoidal Solar Active Regions

Astrophysics, 2020
Four active regions (AR) of the sun are studied. Observational data were obtained from directly visible (line of sight) sharp_cea_720s SDO/HMI magnetograms. The data for each AR were processed by a least squares method in an ellipse. Using a sequence of images after processing the data in all the AR, oscillations of the major and minor axes of the ...
G. Dumbadze, B. Shergelashvili
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Spectra of Solar Activity Regions

1965
From the brilliant lecture of Professor Minnaert we have learned how poor our knowledge is of the physical state of the undisturbed quiet solar atmosphere. But if we turn our attention to the phenomena of solar activity the position is still worse because only during the two past decades we accumulated more or less systematically important ...
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Helicity of Solar Active Regions with Solar Cycles

EAS Publications Series, 2012
The helicity is an important quantity to present the basic topological configuration of magnetic field in the solar atmosphere. In this paper, we present the observational magnetic helicity in solar active regions with solar cycles and the corresponding possible model.
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Properties of Solar Active Regions

1972
‘Solar activity’ is a rather general term for quite a number of different phenomena occurring in the photosphere, in the chromosphere and in the corona. These ‘active’ phenomena are: (1) structures such as spots, plages, filaments, flares and coronal condensations; (2) gradual and impulsive enhancements of radiation in the EUV, X-ray and radio region ...
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Development of Solar Active Regions

2013
The birth, growth, and decay of solar active regions are described. The appearance of active regions in different atmospheric layers is examined, and the coronal extension of active regions is considered. The use of Skylab soft X-ray and extreme UV observations for studying the complex loop structure of active regions in the solar corona and the ...
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Representing Solar Active Regions with Triangulations

1998
The solar chromosphere consists of three classes which contribute differently to ultraviolet radiation reaching the earth. We describe a data set of solar images, means of segmenting the images into the constituent classes, and a novel high-level representation for compact objects based on a triangulated spatial ‘membership function’.
Michael J. Turmon, Saleem Mukhtar
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Current convection in solar active regions

Solar Physics, 1993
Current carrying magnetic fields which penetrate sunspots can be unstable to current convective modes caused by the large gradient of electrical conductivity. The linear growth rates and wavelengths of the unstable modes are found. The unstable modes produce fine-scale vortices perpendicular to the magnetic field, which overshoot well into the solar ...
V. P. Meytlis, H. R. Strauss
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