On a more precise calculation of the electric conductivity in the photosphere and in sunspots

Kopecký, M.; Kuklin, G. V.

doi:10.1007/bf00150949

Cited by 20 publications

(6 citation statements)

References 14 publications

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“…3 shows the histograms of the energy dissipated by the electrical currents (ohmic energy) in the region under study integrated between the 0 and 200 km level (black). The ohmic energy has been calculated using the longitudinal electrical conductivity following Kopecký & Kuklin (1969) and is negligible in the inner sunspot penumbra compared with the solar flux. The energy is dissipated only at the borders of the horizontal tubes, where J reaches significant values (red line).…”

Section: Resultsmentioning

confidence: 99%

The Electrical Current Density Vector in the Inner Penumbra of a Sunspot

Puschmann¹,

Cobo²,

Pillet³

2010

ApJ

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We determine the entire electrical current density vector in a geometrical 3D volume of the inner penumbra of a sunspot from an inversion of spectropolarimetric data obtained with Hinode/SP. Significant currents are seen to wrap around the hotter, more elevated regions with lower and more horizontal magnetic field that harbor strong upflows and radial outflows (the intraspines). The horizontal component of the current density vector is 3-4 times larger than the vertical; nearly all previous studies only obtain the vertical component J z and thus strongly underestimate the current density. The current density J and the magnetic field B form an angle of about 20 • . The plasma β at the 0 km level is larger than 1 in the intraspines and is one order of magnitude lower in the background component of the penumbra (spines). At the 200 km level, the plasma β is below 0.3 nearly everywhere. The plasma β surface as well as the surface optical depth unity are very corrugated. At the borders of intraspines and inside, B is not force-free at deeper layers and nearly force free at the top layers. The magnetic field of the spines is close to being potential everywhere. The dissipated ohmic energy is five orders of magnitudes smaller than the solar energy flux and thus negligible for the energy balance of the penumbra.

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Section: Resultsmentioning

confidence: 99%

The Electrical Current Density Vector in the Inner Penumbra of a Sunspot

Puschmann¹,

Cobo²,

Pillet³

2010

ApJ

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“…(A.4)) and σ the electric conductivity, computed following Kopecký & Kuklin (1969). Figure 4 shows the simulation results at y = 2083 km.…”

Section: Ohmic Dissipation As the Only Source Of Energymentioning

confidence: 99%

Heat transfer in sunspot penumbrae

Cobo

Rubio²

2008

A&A

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Context. Observations at 0. 1 have revealed the existence of dark cores in the bright filaments of sunspot penumbrae. Expectations are high that such dark-cored filaments are the basic building blocks of the penumbra, but their nature remains unknown. Aims. We investigate the origin of dark cores in penumbral filaments and the surplus brightness of the penumbra. To that end we use an uncombed penumbral model. Methods. The 2D stationary heat transfer equation is solved in a stratified atmosphere consisting of nearly horizontal magnetic flux tubes embedded in a stronger and more vertical field. The tubes carry an Evershed flow of hot plasma. Results. This model produces bright filaments with dark cores as a consequence of the higher density of the plasma inside the tubes, which shifts the surface of optical depth unity toward higher (cooler) layers. Our calculations suggest that the surplus brightness of the penumbra is a natural consequence of the Evershed flow, and that magnetic flux tubes about 250 km in diameter can explain the morphology of sunspot penumbrae.

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“…Ïðîâåäåì àíàëèç êîýôôèöèåíòîâ ïðîâîäèìîñòåé. Ãàçîêèíå òè ÷åñêàÿ ïðîâîäèìîñòü âû÷èñëÿëàñü ïî ôîðìóëå [15]: lg s =15.00 + 0.93 lg(P e /P),…”

Section: ïðîñòðàíñòâåííàß íåîäíîðîäíîñòü ìàãíèòíîãî ïîëß â àêòèâíûõ îmentioning

confidence: 99%

On the role of MHD turbulence in the decrease of electric conductivity of plasma in the active magnetic area of the Sun

Krivodubskij¹

2019

Kinemat. fiz. nebesnyh tel (Online)

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On a more precise calculation of the electric conductivity in the photosphere and in sunspots

Cited by 20 publications

References 14 publications

The Electrical Current Density Vector in the Inner Penumbra of a Sunspot

The Electrical Current Density Vector in the Inner Penumbra of a Sunspot

Heat transfer in sunspot penumbrae

On the role of MHD turbulence in the decrease of electric conductivity of plasma in the active magnetic area of the Sun

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