scholarly journals Decametric Radiations from a Large Scale Magnetic Loop in the Solar Corona.

1994 ◽  
Vol 46 (2) ◽  
pp. 97-105
Author(s):  
Takashi Aoyama ◽  
Hiroshi Oya
Keyword(s):  
Solar Corona ◽  
Large Scale ◽  
Magnetic Loop

scholarly journals Propagation of an MHD Shock in the Vicinity of a Magnetic Neutral Sheet

1980 ◽  
Vol 91 ◽  
pp. 323-326
Author(s):  
D. J. Mullan ◽  
R. S. Steinolfson
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Solar Corona ◽  
Large Scale ◽  
Field Structure ◽  
Neutral Sheet ◽  
Solar Cosmic Rays ◽  
Magnetic Field Structure ◽  
Large Scale Magnetic Field ◽  
Highly Correlated

The acceleration of solar cosmic rays in association with certain solar flares is known to be highly correlated with the propagation of an MHD shock through the solar corona (Svestka, 1976). The spatial structure of the sources of solar cosmic rays will be determined by those regions of the corona which are accessible to the flare-induced shock. The regions to which the flare shock is permitted to propagate are determined by the large scale magnetic field structure in the corona. McIntosh (1972, 1979) has demonstrated that quiescent filaments form a single continuous feature (a “baseball stitch”) around the surface of the sun. It is known that helmet streamers overlie quiescent filaments (Pneuman, 1975), and these helmet streamers contain large magnetic neutral sheets which are oriented essentially radially. Hence the magnetic field structure in the low solar corona is characterized by a large-scale radial neutral sheet which weaves around the entire sun following the “baseball stitch”. There is therefore a high probability that as a shock propagates away from a flare, it will eventually encounter this large neutral sheet.

The Large-Scale Density Structure of the Solar Corona and the Heliospheric Current Sheet

1996 ◽  
Vol 458 ◽  
pp. 817 ◽  
Author(s):  
Madhulika Guhathakurta ◽  
Thomas E. Holzer ◽  
R. M. MacQueen
Keyword(s):  
Solar Corona ◽  
Current Sheet ◽  
Large Scale ◽  
Heliospheric Current Sheet ◽  
Density Structure

scholarly journals Coronal global EIT waves as tools for multiple diagnostics

2007 ◽  
Vol 3 (S247) ◽  
pp. 243-250
Author(s):  
I. Ballai ◽  
M. Douglas
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Solar Disk ◽  
Coronal Loop ◽  
Large Scale ◽  
Theoretical Models ◽  
Coronal Loops ◽  
Quiet Sun ◽  
Propagating Waves ◽  
Global Magnetic Field

AbstractObservations in EUV lines of the solar corona revealed large scale propagating waves generated by eruptive events able to travel across the solar disk for large distances. In the low corona, CMEs are known to generate, e.g. EIT waves which can be used to sample the coronal local and global magnetic field. This contribution presents theoretical models for finding values of magnetic field in the quiet Sun and coronal loops based on the interaction of global waves and local coronal loops as well as results on the generation and propagation of EIT waves. The physical connection between local and global solar coronal events (e.g. flares, EIT waves and coronal loop oscillations) will also be explored.

Including the Transition Region in Models of the Large‐Scale Solar Corona

2001 ◽  
Vol 546 (1) ◽  
pp. 542-551 ◽  
Author(s):  
Roberto Lionello ◽  
Jon A. Linker ◽  
Zoran Mikić
Keyword(s):  
Solar Corona ◽  
Transition Region ◽  
Large Scale

scholarly journals The Large-Scale Structure of the Corona

1980 ◽  
Vol 5 ◽  
pp. 549-556
Author(s):  
Jack B. Zirker
Keyword(s):  
Solar Corona ◽  
White Light ◽  
Large Scale ◽  
Dimensional Space ◽  
Coronal Holes ◽  
Solar Limb ◽  
Active Regions ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Fast Wind

The solar corona serves as a prototype of the outer atmospheres of all cool stars. Because of its nearness we can study this prototype in more detail than any other example. Considerable progress has been made recently in understanding how the large scale structure of the solar corona controls the genesis of the solar wind and the distribution of slow and fast wind streams throughout the three-dimensional space surrounding the sun. In this review we will discuss some of the progress made in this field during the last few years. We will emphasize the observational data and the inferences that can be made more or less directly from them. T. Holzer will discuss the theoretical aspects of stellar wind acceleration in another paper in this symposium.The large scale structures of the solar corona consist essentially of three kinds: streamers, active regions and coronal holes. Figure 1 is a familiar photograph of the solar corona, obtained in white light at the total eclipse of 30 June 1973 by the High Altitude Observatory. The streamers are the petal-like structures extending out from the black lunar limb. They taper to narrow radial spikes that have been traced out as far as 10-12 solar radii (Keller, 1979). Daily measurements of the white light corona at the Mauna Loa Observatory (Hundhausen et al. 1979) and the Pic-du-Midi Observatory (Dollfus et al., 1977) since 1965 show that the streamers are fan-shaped structures that may extend 120° in solar longitude. We see them in various perspectives at the solar limb.

scholarly journals The contribution of X-ray polar blowout jets to the solar wind mass and energy

2013 ◽  
Vol 8 (S300) ◽  
pp. 239-242 ◽  
Author(s):  
Giannina Poletto ◽  
Alphonse C. Sterling ◽  
Stefano Pucci ◽  
Marco Romoli
Keyword(s):  
Solar Wind ◽  
Kinetic Energy ◽  
Energy Budget ◽  
Coronal Mass Ejections ◽  
Mass Flux ◽  
Large Scale ◽  
Coronal Holes ◽  
Magnetic Loop ◽  
Small Scale ◽  
X Ray

AbstractBlowout jets constitute about 50% of the total number of X-ray jets observed in polar coronal holes. In these events, the base magnetic loop is supposed to blow open in what is a scaled-down representation of two-ribbon flares that accompany major coronal mass ejections (CMEs): indeed, miniature CMEs resulting from blowout jets have been observed. This raises the question of the possible contribution of this class of events to the solar wind mass and energy flux. Here we make a first crude evaluation of the mass contributed to the wind and of the energy budget of the jets and related miniature CMEs, under the assumption that small-scale events behave as their large-scale analogs. This hypothesis allows us to adopt the same relationship between jets and miniature-CME parameters that have been shown to hold in the larger-scale events, thus inferring the values of the mass and kinetic energy of the miniature CMEs, currently not available from observations. We conclude our work estimating the mass flux and the energy budget of a blowout jet, and giving a crude evaluation of the role possibly played by these events in supplying the mass and energy that feeds the solar wind.

scholarly journals Occultations of the Crab Nebula by the Solar Corona in June 1957 and 1958

1959 ◽  
Vol 12 (2) ◽  
pp. 134 ◽  
Author(s):  
OB Slee
Keyword(s):  
Solar Corona ◽  
Large Scale ◽  
Crab Nebula ◽  
Angular Separation ◽  
Pencil Beam ◽  
Scattering Process ◽  
Short Term ◽  
Transmission Properties ◽  
The Crab Nebula ◽  
Comparable Magnitude

A description is given of some observations of the occultations of the Crab nebula by the solar corona in June 1957 and 1958, obtained with pencil-beam, fan-beam, and interferometer-type instruments. It is shown that the distribution of 85� 5 Mc/s radiation on days when the angular separation is less than 10 solar radii is not consistent with a symmetrical scattering process. Better agreement is obtained by postulating the existence of scattering and regular refraction of comparable magnitude. Certain unexplained features of the pencil-beam distributions indicate that large-scale electron irregularities may be important in the scattering and refraction process. Additional evidence is presented for very short-term changes in the transmission properties of the corona.

scholarly journals Comparing extrapolations of the coronal magnetic field structure at 2.5R⊙with multi-viewpoint coronagraphic observations

2019 ◽  
Vol 627 ◽  
pp. A9 ◽  
Author(s):  
C. Sasso ◽  
R. F. Pinto ◽  
V. Andretta ◽  
R. A. Howard ◽  
A. Vourlidas ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Large Scale ◽  
Solar Rotation ◽  
Coronal Holes ◽  
Coronal Magnetic Field ◽  
Central Meridian ◽  
Fast Method ◽  
The Many ◽  
The Magnetic Field

The magnetic field shapes the structure of the solar corona, but we still know little about the interrelationships between the coronal magnetic field configurations and the resulting quasi-stationary structures observed in coronagraphic images (such as streamers, plumes, and coronal holes). One way to obtain information on the large-scale structure of the coronal magnetic field is to extrapolate it from photospheric data and compare the results with coronagraphic images. Our aim is to verify whether this comparison can be a fast method to systematically determine the reliability of the many methods that are available for modeling the coronal magnetic field. Coronal fields are usually extrapolated from photospheric measurements that are typically obtained in a region close to the central meridian on the solar disk and are then compared with coronagraphic images at the limbs, acquired at least seven days before or after to account for solar rotation. This implicitly assumes that no significant changes occurred in the corona during that period. In this work, we combine images from three coronagraphs (SOHO/LASCO-C2 and the two STEREO/SECCHI-COR1) that observe the Sun from different viewing angles to build Carrington maps that cover the entire corona to reduce the effect of temporal evolution to about five days. We then compare the position of the observed streamers in these Carrington maps with that of the neutral lines obtained from four different magnetic field extrapolations to evaluate the performances of the latter in the solar corona. Our results show that the location of coronal streamers can provide important indications to distinguish between different magnetic field extrapolations.

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