Energy release in the solar corona from spatially resolved magnetic braids

Nature ◽  
2013 ◽  
Vol 493 (7433) ◽  
pp. 501-503 ◽  
Author(s):  
J. W. Cirtain ◽  
L. Golub ◽  
A. R. Winebarger ◽  
B. De Pontieu ◽  
K. Kobayashi ◽  
...  
Keyword(s):  
Solar Corona ◽  
Energy Release ◽  
Spatially Resolved

scholarly journals Eclipse mapping at X-ray wavelengths

1996 ◽  
Vol 176 ◽  
pp. 85-94 ◽  
Author(s):  
J.H.M.M. Schmitt
Keyword(s):  
Solar Corona ◽  
Binary Systems ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Similar Amount ◽  
Inversion Problem ◽  
X Ray ◽  
Three Dimensional Structure ◽  
Spatially Resolved ◽  
Rotational Modulation

Stellar coronae cannot be spatially resolved, and yet stellar coronae are likely to exhibit a similar amount of structure as the solar corona. Currently, the only way to infer structure from spatially unresolved data is to look for rotational modulation of the X-ray emission or eclipses in the case of binary systems. I will discuss some of the observations obtained and critically review the methods used to infer structure from these data. Particular emphasis will be placed on the ill-conditioned nature of the inversion problem, that makes it next to impossible to infer the possibly three-dimensional structure of stellar coronae.

scholarly journals Stellar Coronae

1980 ◽  
Vol 5 ◽  
pp. 419-428 ◽  
Author(s):  
G. S. Vaiana
Keyword(s):  
Magnetic Fields ◽  
Solar Corona ◽  
Main Sequence ◽  
High Energy ◽  
Coronal Heating ◽  
Standard Theory ◽  
Plasma Structure ◽  
X Ray ◽  
Spatially Resolved ◽  
Surface Convection

The standard theory of stellar coronae requires the presence of vigorous surface convection. In consequence, the expectation of such a theory is that stellar x-ray emission — if due to a corona — should be limited to a subset of stars (principally those of main sequence spectral types F and G), and therefore should be relatively rare. This theory also makes detailed predictions about coronal heating, which are subject to test if spatially resolved coronal data are available. We are now in a position to subject the standard coronal scenarios to observational scrutiny on both counts: Skylab and later observations have supplied us with spatially resolved data of the solar corona, while the succession of high-energy x-ray astronomy satellites, culminating with EINSTEIN, now gives us a long-awaited glimpse of stellar x-ray emission throughout the K-R diagram.I will maintain that these new data imply that coronal x-ray emission dominantly derives from plasma structure confined by stellar surface magnetic fields; that coronal heating is likely to be non-acoustic in character and involves the confining magnetic fields; that stellar x-ray emission is not well correlated with the level of surface convection activity. These results of course cast serious doubt upon the viability of the standard theory of stellar coronal formation. In the following, I will try to very briefly summarize the solar and stellar data, to present the context in which they were initially obtained, and very briefly sketch the new coronal picture we are pursuing. The results presented here are excerpted from lectures presented by R. Rosner and myself recently at Erice, Italy (viz. Vaiana 1979) and from the preliminary results of the EINSTEIN Stellar Survey (Vaiana et al. 1979). The latter, part of a larger effort in x-ray astronomy led by R. Giacconi, involves the work of many people, including F.R. Harnden, L. Golub, P. Gorenstein, R. Rosner, F. Seward, K. Topika at CFA, as well as a number of EINSTEIN guest investigators.

scholarly journals Mechanisms for Coronal Mass Supply by Evaporative Micro-Events

2001 ◽  
Vol 203 ◽  
pp. 498-500
Author(s):  
J. C. Brown ◽  
S. Krucker ◽  
M. Güdel ◽  
A. O. Benz
Keyword(s):  
Solar Corona ◽  
Energy Release ◽  
Thermal Conduction ◽  
Major Part ◽  
Coronal Loops ◽  
Transport Mechanisms ◽  
Chromospheric Evaporation

There is extensive evidence from SoHO and other data that “micro-events” play an important role in sustaining at least some components of the solar corona. These are often termed coronal micro-” heating events” though a major part of their role is feeding coronal loops through chromospheric evaporation. We consider what can be learnt from these data concerning the energy release and transport mechanisms driving the evaporation, including thermal conduction and fast particles. We conclude, from one large event and the statistics of many small ones, that conductive evaporation alone does not fit observations and that fast particles or some other nonthermal driver must be involved.

Magnetic field value in the weak energy release region of the solar corona

1994 ◽  
Vol 37 (7) ◽  
pp. 569-574
Author(s):  
B. N. Levin ◽  
V. M. Fridman ◽  
O. A. Sheiner
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Energy Release ◽  
Energy Release Region

Magnetic reconnection and energy release in the solar corona by Taylor relaxation

Solar Physics ◽  
1991 ◽  
Vol 131 (2) ◽  
pp. 297-318 ◽  
Author(s):  
G. E. Vekstein ◽  
E. R. Priest ◽  
C. D. C. Steele
Keyword(s):  
Solar Corona ◽  
Magnetic Reconnection ◽  
Energy Release ◽  
Taylor Relaxation

Colour Photometry of the Solar Corona of July 11, 1991

1994 ◽  
Vol 144 ◽  
pp. 597-599 ◽  
Author(s):  
I. V. Alexeyeva ◽  
N. L. Kroussanova ◽  
M. V. Streltsova
Keyword(s):  
Solar Corona ◽  
Red Emission ◽  
Coronal Structures

AbstractThe results of photometry of colour positives of the solar corona of July 11, 1991 are presented. Observations of the white corona were made without radial niters in Jojutla (Mexico). Dependences of coronal brightness on distance in the red (640 nm) and blue (420 nm) wavelength intervals are deduced for different coronal structures up to 3.0-3.5R⊙. The effect of ”reddening“ is noted. The excess of the red emission to the blue one (I640nm/I420nm) is found to be 1.20 and 1.17 at distance of 2.2R⊙for the N-E helmet streamer (P ≃ 37°) and the N-W region of low brightness (P ≃ 339°), respectively.

July 11, 1991 Eclipse Corona Photometry by the Results of Electropolarimetric and CCD-Matrix Observations

1994 ◽  
Vol 144 ◽  
pp. 567-569
Author(s):  
V. Kulidzanishvili ◽  
D. Georgobiani
Keyword(s):  
Solar Corona ◽  
Observational Data ◽  
Solar Limb ◽  
Ccd Matrix

AbstractThe observational data of July 11, 1991 eclipse solar corona obtained by both electropolarimeter (EP) and CCD-matrix were processed. Using these data, the solar corona photometry was carried out. The results of EP data are compared with the ones of CCD data. It must be noted here that the CCD data give us only characteristics of the inner corona, while the EP data show the features of both the inner and middle corona up to 4R⊙. Standard flattening indexϵis evaluated from both data. The dependence of the flattening index on the distance from the solar limb is investigated. The isophotes in Na and Ca lines are plotted. Based on these data some ideas and conclusions on the type of the solar corona are presented.

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

1994 ◽  
Vol 144 ◽  
pp. 559-564
Author(s):  
P. Ambrož ◽  
J. Sýkora
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Coronal Magnetic Field ◽  
Coronal Magnetic Fields ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

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