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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
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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
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wavelengths have shown a systematic red-shift. The
Evershed effect is common to every spectral line formed at a temperature below 10 K; this fact would imply a constant downflow from the
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Reale, F.; Serio, S.; Peres, G. (1996). "Radiatively-driven downdrafts and redshifts in transition region lines. I. Reference model".
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78:. The observed velocity is about 5 km/s. Of course, this is impossible, since if it were true, the
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Meyer, F.; Schmidt, H.U. (1968). "Magnetisch ausgerichtete Strömungen zwischen
Sonnenflecken".
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500:"A new interpretation of the redshift observed in optically thin transition region lines"
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The effect was commemorated in a postage stamp issued in India on 2 December 2008.
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at temperatures of million degrees over distances much larger than a solar radius.
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Kjeldseth-Moe; Brynildsen, N.; Brekke, P.; Engvold, O.; et al. (1988).
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would disappear in a short time instead of being suspended over the
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418:"The origin of spicules and heating of the lower transition region"
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377:"Dynamics and spectroscopy of asymmetrically heated coronal loops"
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571:. Department of Posts, Government of India. Archived from
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different cross-sections of the coronal loops footpoints,
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236:
Biographical
Memoirs of Fellows of the Royal Society
459:"Gas flows in the transition region above sunspots"
278:Monthly Notices of the Royal Astronomical Society
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8:
97:In synthesis, the proposed mechanisms are:
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62:Afterwards, measurements of the spectral
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27:, is the radial flow of gas across the
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375:Mariska, j.T.; Boris, J.P. (1983).
315:"Centenary of a solar observatory"
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51:in India, when he found that the
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105:driven by a pressure difference,
39:from the inner border with the
274:"Radial movement in sun-spots"
1:
127:thermal instabilities during
613:. You can help Knowledge by
49:Kodaikanal Solar Observatory
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542:Astronomy and Astrophysics
313:Subramanian, T.S. (1999).
129:chromospheric condensation
20:, named after the British
504:The Astrophysical Journal
463:The Astrophysical Journal
422:The Astrophysical Journal
381:The Astrophysical Journal
231:"John Evershed 1864-1956"
498:Hansteen, Viggo (1993).
43:towards the outer edge.
555:1996A&A...316..215R
609:-related article is a
299:10.1093/mnras/69.5.454
250:10.1098/rsbm.1957.0004
665:Emission spectroscopy
350:Z. Angew. Math. Mech.
272:Evershed, J. (1909).
416:Athay, R.G. (1984).
325:(13). Archived from
516:1993ApJ...402..741H
475:1988ApJ...334.1066K
434:1984ApJ...287..412A
393:1983ApJ...267..409M
362:1968ZaMM...48..218M
290:1909MNRAS..69..454E
153:Solar System portal
55:of sunspots showed
675:Spectroscopy stubs
227:Stratton, F. J. M.
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575:on 12 August 2013
72:transition region
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670:Plasma phenomena
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167:Astronomy portal
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101:siphon flows in
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660:Solar phenomena
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569:"Stamps - 2008"
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329:on 17 July 2012
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118:multiple flows,
66:emitted in the
31:surface of the
18:Evershed effect
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284:(5): 454–458.
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208:Plasma physics
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181:Physics portal
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111:the return of
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64:emission lines
53:spectral lines
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57:doppler shift
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25:John Evershed
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615:expanding it
607:spectroscopy
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577:. Retrieved
573:the original
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331:. Retrieved
327:the original
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203:Spectroscopy
195:Space portal
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76:chromosphere
74:towards the
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29:photospheric
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68:ultraviolet
654:Categories
214:References
122:nanoflares
92:on average
22:astronomer
319:Frontline
243:: 40–51.
579:2 August
469:: 1066.
333:27 April
229:(1957).
139:See also
113:spicules
37:sunspots
33:penumbra
551:Bibcode
549:: 215.
512:Bibcode
510:: 741.
471:Bibcode
430:Bibcode
428:: 412.
389:Bibcode
387:: 409.
358:Bibcode
356:: 218.
286:Bibcode
259:769351
257:
80:corona
605:This
255:JSTOR
124:, and
41:umbra
611:stub
581:2013
335:2013
16:The
547:316
520:doi
508:402
479:doi
467:334
438:doi
426:287
397:doi
385:267
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245:doi
84:Sun
35:of
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241:3
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