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Hénoux, J.C.; Chambe, G.; Smith, D.; Tamres, D.; Feautrier, N.; Rovira, M.; Sahal-Bréchot, S. "Impact line linear polarization as a diagnostic of 100 keV proton acceleration in solar flares" (1990) Astrophysical Journal, Supplement Series. 73(2):303-311
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Abstract:

Hard X-ray emission is generally interpreted as bremsstrahlung of 10-100 keV electron beams. This requires a high number of electrons to explain the intense X-ray flux observed. An interesting suggestion was made recently that 100 keV proton beams bombarding the atmosphere would create a hot thermal plasma at the origin of the observed X-ray emission. Such low-energy protons have never been detected. We propose to use impact linear polarization of chromospheric lines as a diagnostic of 100 keV protons. Recent observations of Ha linear polarization in solar flares are presented. A polarization degree as high as 2.5% is observed in some Hα -bright patches. The electric vector is radial. This polarization is interpreted as impact polarization by low-energy protons. From existing observations we cannot discriminate between local and nonlocal origins of the detected population of energetic particles. However, we show that nonlocal proton acceleration leading to chromospheric bombardment is a likely explanation of the observed polarization. Whatever the initial distribution, transport effects in the chromosphere generate an anisotropic velocity distribution for protons. The required initial minimum energy and energy flux above this energy in the corona are found to be respectively 200 keV and 3 × 108 ergs cm-2 s-1 for a 107 K corona of mass 3×10-4 g cm-2. These results are valid as long as a possible scattering by waves is not strong enough for increasing the particle path in the corona.

Registro:

Documento: Artículo
Título:Impact line linear polarization as a diagnostic of 100 keV proton acceleration in solar flares
Autor:Hénoux, J.C.; Chambe, G.; Smith, D.; Tamres, D.; Feautrier, N.; Rovira, M.; Sahal-Bréchot, S.
Filiación:Observatoire de Paris
Berkeley Research Associates, Inc.
Department of Physics, Centre College, Danville, KY, United States
Inst. Astronomia y Fis. del Espacio, Buenos Aires, Argentina
Observatoire de Paris, DASOP-UA326, 92195 Meudon Principal Cedex, France
Observatoire de Paris, DAMAP-UA812, 92195 Meudon Principal Cedex, France
Inst. Astronomia y Fis. del Espacio, 1428 Buenos Aires, Argentina
Berkeley Research Associates, Inc., P. O. Box 241, Berkeley, CA 94701, United States
Department of Physics, Centre College, Danville, KY 40422, United States
Palabras clave:Particle acceleration; Polarization; Sun: flares; Sun: particle emission; Sun: X-rays
Año:1990
Volumen:73
Número:2
Página de inicio:303
Página de fin:311
DOI: http://dx.doi.org/10.1086/191466
Título revista:Astrophysical Journal, Supplement Series
Título revista abreviado:Astrophys. J. Suppl. Ser.
ISSN:00670049
Registro:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00670049_v73_n2_p303_Henoux

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Citas:

---------- APA ----------
Hénoux, J.C., Chambe, G., Smith, D., Tamres, D., Feautrier, N., Rovira, M. & Sahal-Bréchot, S. (1990) . Impact line linear polarization as a diagnostic of 100 keV proton acceleration in solar flares. Astrophysical Journal, Supplement Series, 73(2), 303-311.
http://dx.doi.org/10.1086/191466
---------- CHICAGO ----------
Hénoux, J.C., Chambe, G., Smith, D., Tamres, D., Feautrier, N., Rovira, M., et al. "Impact line linear polarization as a diagnostic of 100 keV proton acceleration in solar flares" . Astrophysical Journal, Supplement Series 73, no. 2 (1990) : 303-311.
http://dx.doi.org/10.1086/191466
---------- MLA ----------
Hénoux, J.C., Chambe, G., Smith, D., Tamres, D., Feautrier, N., Rovira, M., et al. "Impact line linear polarization as a diagnostic of 100 keV proton acceleration in solar flares" . Astrophysical Journal, Supplement Series, vol. 73, no. 2, 1990, pp. 303-311.
http://dx.doi.org/10.1086/191466
---------- VANCOUVER ----------
Hénoux, J.C., Chambe, G., Smith, D., Tamres, D., Feautrier, N., Rovira, M., et al. Impact line linear polarization as a diagnostic of 100 keV proton acceleration in solar flares. Astrophys. J. Suppl. Ser. 1990;73(2):303-311.
http://dx.doi.org/10.1086/191466