Dynamical Response of the Solar Corona. II. Numerical Simulations Near the Sun

1976 ◽  
Vol 207 ◽  
pp. 300 ◽  
Author(s):  
Richard S. Steinolfson ◽  
Yoshinari Nakagawa
2019 ◽  
Vol 623 ◽  
pp. A176 ◽  
Author(s):  
L. P. Chitta ◽  
A. R. C. Sukarmadji ◽  
L. Rouppe van der Voort ◽  
H. Peter

Context. Densely packed coronal loops are rooted in photospheric plages in the vicinity of active regions on the Sun. The photospheric magnetic features underlying these plage areas are patches of mostly unidirectional magnetic field extending several arcsec on the solar surface. Aims. We aim to explore the transient nature of the magnetic field, its mixed-polarity characteristics, and the associated energetics in the active region plage using high spatial resolution observations and numerical simulations. Methods. We used photospheric Fe I 6173 Å spectropolarimetric observations of a decaying active region obtained from the Swedish 1-m Solar Telescope (SST). These data were inverted to retrieve the photospheric magnetic field underlying the plage as identified in the extreme-ultraviolet emission maps obtained from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). To obtain better insight into the evolution of extended unidirectional magnetic field patches on the Sun, we performed 3D radiation magnetohydrodynamic simulations of magnetoconvection using the MURaM code. Results. The observations show transient magnetic flux emergence and cancellation events within the extended predominantly unipolar patch on timescales of a few 100 s and on spatial scales comparable to granules. These transient events occur at the footpoints of active region plage loops. In one case the coronal response at the footpoints of these loops is clearly associated with the underlying transient. The numerical simulations also reveal similar magnetic flux emergence and cancellation events that extend to even smaller spatial and temporal scales. Individual simulated transient events transfer an energy flux in excess of 1 MW m−2 through the photosphere. Conclusions. We suggest that the magnetic transients could play an important role in the energetics of active region plage. Both in observations and simulations, the opposite-polarity magnetic field brought up by transient flux emergence cancels with the surrounding plage field. Magnetic reconnection associated with such transient events likely conduits magnetic energy to power the overlying chromosphere and coronal loops.


1959 ◽  
Vol 9 ◽  
pp. 3-7
Author(s):  
F. G. Smith

Radio astronomy has been expanding into outer space so fast in recent years that it is pleasant to find our own solar system at last receiving the attention it deserves. In this session we are concerned with everything within the system except the sun and our own planet. I start with a question, to which I shall return later: Where does the sun end? In another session you will hear of the experiments on the far-out parts of the solar corona; here we are concerned with interplanetary space as well as with the planets themselves, and what lies within this region may or may not be considered part of the solar corona.


2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Antonio Fernando Bertachini de Almeida Prado

The present paper has the goal of developing a new criterion to search for orbits that minimize the fuel consumption for station-keeping maneuvers. This approach is based on the integral over the time of the perturbing forces. This integral measures the total variation of velocity caused by the perturbations in the spacecraft, which corresponds to the equivalent variation of velocity that an engine should deliver to the spacecraft to compensate the perturbations and to keep its orbit Keplerian all the time. This integral is a characteristic of the orbit and the set of perturbations considered and does not depend on the type of engine used. In this sense, this integral can be seen as a criterion to select the orbit of the spacecraft. When this value becomes larger, more consumption of fuel is required for the station keeping, and, in this sense, less interesting is the orbit. This concept can be applied to any perturbation. In the present research, as an example, the perturbation caused by a third body is considered. Then, numerical simulations considering the effects of the Sun and the Moon in a satellite around the Earth are shown to exemplify the method.


2000 ◽  
Vol 195 ◽  
pp. 455-459
Author(s):  
E. N. Parker

The Sun serves as the local physics laboratory for studying the suprathermal activity phenomena of stars. Scrutiny of the Sun has led to the discovery of a host of previously unknown physical effects, largely within the classical physics of Newton and Maxwell, but including quantum mechanics and lepton physics as well.


1957 ◽  
Vol 4 ◽  
pp. 356-357 ◽  
Author(s):  
A. Schlüter

The shift of the emitted frequencies towards lower frequencies during a solar outburst is usually interpreted as due to a progressive rarefaction of the emitting gas. If one assumes that the emitted frequency is identical with the plasma frequency and furthermore that the density of the emitting plasma is similar to the density of the solar corona at the location of the radiating material, then it follows that this material is subject to an acceleration throughout the solar corona which compensates or exceeds the effect of the gravitational field of the sun.


1996 ◽  
Vol 17 (3) ◽  
pp. 57-60 ◽  
Author(s):  
M. Pätzold ◽  
F.M. Neubauer ◽  
B. Häusler ◽  
W. Eidel ◽  
M.K. Bird
Keyword(s):  
The Sun ◽  

2006 ◽  
Vol 653 (1) ◽  
pp. 765-773 ◽  
Author(s):  
Tamara M. Rogers ◽  
Gary A. Glatzmaier ◽  
C. A. Jones

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