The Evershed effect, named after the British astronomer John Evershed, is the radial flow of gas across the photospheric surface of the penumbra of sunspots from the inner border with the umbra towards the outer edge. Many theories have been proposed to explain this redshift in line profiles of the transition region, but the problem is still unsolved, since a coherent theory should take into account all the physical observations: UV line profiles are redshifted on average, but they show back and forth velocity oscillations at the same time. In synthesis, the proposed mechanisms are:
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| - Evershed-Effekt (de)
- Efecto Evershed (es)
- Evershed effect (en)
- Efeito Evershed (pt)
- Эффект Эвершеда (ru)
- 埃弗谢德效应 (zh)
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| - El efecto Evershed, nombrado así en memoria del astrónomo británico John Evershed, es el flujo radial de gas en la fotosfera del Sol a través de la superficie en penumbra de las manchas solares. Se produce a partir de la frontera interior con el umbra hacia el borde exterior. (es)
- 埃弗谢德效应（英語：Evershed effect）由英国天文学家约翰·埃弗谢德于1909年发现，从太阳黑子的本影和半影间，有气体向二边水平輻射流。流速距出发点越运，速度越快，气体流的典型速度为1-4Km每秒，达到太阳黑子外边界处突然停止，这种现象称为埃弗谢德效应。此效应对太阳黑子的形成，稳定和动力过程都起重要作用；而且是太阳物理的基本问题之一。 现在关于埃弗谢德效应的理论主要有二大类： 1.
* 气体在磁通管内作管状流动 2.
* 气体如放长卷作对流式运动 但对其物理机制尚未有统一的认识。 (zh)
- Der Evershed-Effekt ist der radial auswärts gerichtete Fluss von Gas über die photosphärische Oberfläche der Sonne von der Penumbra-Innengrenze eines Sonnenflecks zur Außengrenze der Penumbra. Die Geschwindigkeit des Flusses geht von 1 km pro Sekunde an der Grenze zwischen Umbra und Penumbra bis auf ein Maximum von 2,5 km pro Sekunde in der Mitte der Penumbra. In einzelnen Fällen wurden auch Geschwindigkeiten von 6 km pro Sekunde gemessen. (de)
- The Evershed effect, named after the British astronomer John Evershed, is the radial flow of gas across the photospheric surface of the penumbra of sunspots from the inner border with the umbra towards the outer edge. Many theories have been proposed to explain this redshift in line profiles of the transition region, but the problem is still unsolved, since a coherent theory should take into account all the physical observations: UV line profiles are redshifted on average, but they show back and forth velocity oscillations at the same time. In synthesis, the proposed mechanisms are: (en)
- O efeito Evershed, nomeado em honra do astrónomo britânico John Evershed, é o fluxo radial de gás através da superfície fotoesférica da penumbra de manchas solares, desde a borda interior até ao limite exterior. A velocidade varia desde 1 km/s na borda entre a e a penumbra até a um máximo equivalente ao dobro desse valor no meio da penumbra, descendo até zero no limite exterior da penumbra. Evershed descobriu este fenómeno em Janeiro de 1909, enquanto trabalhava no , na Índia, quando encontrou que as linhas espectrais das manchas solares mostravam o efeito Doppler. (pt)
- Эффект Эвершеда (англ. Evershed effect, иногда называется также эффект Эвершеда—Абетти) — явление в атмосфере Солнца, суть которого в том, что на уровне фотосферы газ со скоростью порядка 2 км/с движется по направлению от центра солнечного пятна наружу, тогда как в хромосфере над пятном происходит движение газа к центру пятна со скоростью до 5 км/с. Название получило в честь английского астронома Джона Эвершеда, открывшего это явление в 1909 году. (ru)
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| - Der Evershed-Effekt ist der radial auswärts gerichtete Fluss von Gas über die photosphärische Oberfläche der Sonne von der Penumbra-Innengrenze eines Sonnenflecks zur Außengrenze der Penumbra. Die Geschwindigkeit des Flusses geht von 1 km pro Sekunde an der Grenze zwischen Umbra und Penumbra bis auf ein Maximum von 2,5 km pro Sekunde in der Mitte der Penumbra. In einzelnen Fällen wurden auch Geschwindigkeiten von 6 km pro Sekunde gemessen. Das Phänomen wurde von dem britischen Astronomen John Evershed (1864–1956) 1909 erstmals beobachtet, als dieser am Kodaikanal Solar Observatory in Indien arbeitete und die Dopplerverschiebung der Spektrallinien in Sonnenflecken untersuchte. (de)
- The Evershed effect, named after the British astronomer John Evershed, is the radial flow of gas across the photospheric surface of the penumbra of sunspots from the inner border with the umbra towards the outer edge. The speed varies from around 1 km/s at the border between the umbra and the penumbra to a maximum of around double this in the middle of the penumbra and falls off to zero at the outer edge of the penumbra.Evershed first detected this phenomenon in January 1909, whilst working at the Kodaikanal Solar Observatory in India, when he found that the spectral lines of sunspots showed doppler shift. Afterwards, measurements of the spectral emission lines emitted in the ultraviolet wavelengths have shown a systematic red-shift. The Evershed effect is common to every spectral line formed at a temperature below 105 K; this fact would imply a constant downflow from the transition region towards the chromosphere. The observed velocity is about 5 km/s. Of course, this is impossible, since if it were true, the corona would disappear in a short time instead of being suspended over the Sun at temperatures of million degrees over distances much larger than a solar radius. Many theories have been proposed to explain this redshift in line profiles of the transition region, but the problem is still unsolved, since a coherent theory should take into account all the physical observations: UV line profiles are redshifted on average, but they show back and forth velocity oscillations at the same time. In synthesis, the proposed mechanisms are:
* siphon flows in coronal loops driven by a pressure difference,
* different cross-sections of the coronal loops footpoints,
* the return of spicules,
* multiple flows,
* nanoflares, and
* thermal instabilities during chromospheric condensation. The effect was commemorated in a postage stamp issued in India on 2 December 2008. (en)
- El efecto Evershed, nombrado así en memoria del astrónomo británico John Evershed, es el flujo radial de gas en la fotosfera del Sol a través de la superficie en penumbra de las manchas solares. Se produce a partir de la frontera interior con el umbra hacia el borde exterior. (es)
- O efeito Evershed, nomeado em honra do astrónomo britânico John Evershed, é o fluxo radial de gás através da superfície fotoesférica da penumbra de manchas solares, desde a borda interior até ao limite exterior. A velocidade varia desde 1 km/s na borda entre a e a penumbra até a um máximo equivalente ao dobro desse valor no meio da penumbra, descendo até zero no limite exterior da penumbra. Evershed descobriu este fenómeno em Janeiro de 1909, enquanto trabalhava no , na Índia, quando encontrou que as linhas espectrais das manchas solares mostravam o efeito Doppler. Posteriormente, medições das linhas de emissão espectrais emitidas nos comprimentos de onda ultravioletas, mostraram um desvio para o vermelho sistemático. O efeito Evershed é comum para cada linha espectral formada a temperaturas abaixo de 105 K; este facto implicava um constante fluxo de cima para baixo desde a até à cromosfera. A velocidade observada é de cerca de 5 km/s. Tal seria impossível, visto que a corona desapareceria em pouco tempo em vez de estar suspensa à volta do Sol a temperaturas de milhões de graus a distâncias muito maiores que o raio solar. Muitas teorias foram propostas para explicar este desvio para o vermelho no perfil das linhas na região de transição, mas o problemas ainda está em discussão, uma vez que uma teoria coerente deverá ter em conta todas as observações físicas: os perfis das linhas UV estão desviadas "em média" para o vermelho, mas mostram velocidades oscilatórias ao mesmo tempo. Alguns dos mecanismos propostos são:
* fluxos sifónicos nos anéis coronais devido a diferença de temperatura;
* o retorno de espículas;
* fluxos múltiplos;
* ;
* instabilidades térmicas durante a condensação cromosférica. (pt)
- Эффект Эвершеда (англ. Evershed effect, иногда называется также эффект Эвершеда—Абетти) — явление в атмосфере Солнца, суть которого в том, что на уровне фотосферы газ со скоростью порядка 2 км/с движется по направлению от центра солнечного пятна наружу, тогда как в хромосфере над пятном происходит движение газа к центру пятна со скоростью до 5 км/с. Название получило в честь английского астронома Джона Эвершеда, открывшего это явление в 1909 году. В 2009 году причины этого явления объяснили астрофизики из США и ФРГ с помощью моделирования на суперкомпьютере с быстродействием 76 триллионов операций в секунду (ru)
- 埃弗谢德效应（英語：Evershed effect）由英国天文学家约翰·埃弗谢德于1909年发现，从太阳黑子的本影和半影间，有气体向二边水平輻射流。流速距出发点越运，速度越快，气体流的典型速度为1-4Km每秒，达到太阳黑子外边界处突然停止，这种现象称为埃弗谢德效应。此效应对太阳黑子的形成，稳定和动力过程都起重要作用；而且是太阳物理的基本问题之一。 现在关于埃弗谢德效应的理论主要有二大类： 1.
* 气体在磁通管内作管状流动 2.
* 气体如放长卷作对流式运动 但对其物理机制尚未有统一的认识。 (zh)
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