Origin of the Submillimeter Radio Emission During the Time-Extended Phase of a Solar Flare

Author(s)

Trottet, G. ^{[1, 2]} ; Raulin, J.-P. ^[1] ; de Castro, G. Gimenez ^[1] ; Luethi, T. ^[3] ; Caspi, A. ^[4] ; Mandrini, C. H. ^{[5, 6]} ; Luoni, M. L. ^[5] ; Kaufmann, P. ^{[7, 1]}

Affiliation

^[1] CRAAM Univ Presbiteriana Mackenzie, Sao Paulo - Brazil

^[2] Univ P&M Curie & Paris Diderot, Observ Meudon, LESIA CNRS, Observ Paris, UMR 8109, F-92195 Meudon - France

^[3] Leica Geosyst AG, Hexagon Metrol, CH-5035 Unterenfelden - Switzerland

^[4] Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 - USA

^[5] CONICET UBA, Inst Astron & Fis Espacio, RA-1428 Buenos Aires, DF - Argentina

^[6] FCEN UBA, Fac Ciencias Exactas & Nat, Buenos Aires, DF - Argentina

^[7] Univ Estadual Campinas, Ctr Componentes Semicond, Campinas, SP - Brazil

• Document type: Journal article
• Source: SOLAR PHYSICS; v. 273, n. 2, p. 339-361, NOV 2011.
• Web of Science Citations: 18

Abstract

Solar flares observed in the 200 -aEuro parts per thousand 400 GHz radio domain may exhibit a slowly varying and time-extended component which follows a short (few minutes) impulsive phase and can last for a few tens of minutes to more than one hour. The few examples discussed in the literature indicate that such long-lasting submillimeter emission is most likely thermal bremsstrahlung. We present a detailed analysis of the time-extended phase of the 27 October 2003 (M6.7) flare, combining 1 -aEuro parts per thousand 345 GHz total-flux radio measurements with X-ray, EUV, and H alpha observations. We find that the time-extended radio emission is, as expected, radiated by thermal bremsstrahlung. Up to 230 GHz, it is entirely produced in the corona by hot and cool materials at 7 -aEuro parts per thousand 16 MK and 1 -aEuro parts per thousand 3 MK, respectively. At 345 GHz, there is an additional contribution from chromospheric material at a few 10(4) K. These results, which may also apply to other millimeter-submillimeter radio events, are not consistent with the expectations from standard semiempirical models of the chromosphere and transition region during flares, which predict observable radio emission from the chromosphere at all frequencies where the corona is transparent. (AU)

• FAPESP's process: 09/15880-0 - Analysis and interpretation of high energy processes in solar flares
• Grantee: Pierre Kaufmann
• Support Opportunities: Research Grants - Visiting Researcher Grant - International
• FAPESP's process: 09/18386-7 - Integrated modelling of radio and X-ray emission during solar flares
• Grantee: Carlos Guillermo Giménez de Castro
• Support Opportunities: Regular Research Grants