PLASMA HEATING IN THE VERY EARLY PHASE OF SOLAR FLARES

Journal Article · Tue Nov 10 04:00:00 EST 2009 · Astrophysical Journal (Online)

DOI:https://doi.org/10.1088/0004-637X/705/2/L143· OSTI ID:21378289

Siarkowski, M ^[1]; Falewicz, R; Rudawy, P ^[2]

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1. Space Research Centre, Polish Academy of Sciences, 51-622 Wroclaw, ul. Kopernika 11 (Poland)
2. Astronomical Institute, University of Wroclaw, 51-622 Wroclaw, ul. Kopernika 11 (Poland)

In this Letter, we analyze soft X-ray (SXR) and hard X-ray (HXR) emission of the 2002 September 20 M1.8 GOES class solar flare observed by the RHESSI and GOES satellites. In this flare event, SXR emission precedes the onset of the main bulk HXR emission by approx5 minutes. This suggests that an additional heating mechanism may be at work at the early beginning of the flare. However, RHESSI spectra indicate a presence of the non-thermal electrons also before the impulsive phase. So, we assumed that a dominant energy transport mechanism during the rise phase of solar flares is electron-beam-driven evaporation. We used non-thermal electron beams derived from RHESSI spectra as the heating source in a hydrodynamic model of the analyzed flare. We showed that energy delivered by non-thermal electron beams is sufficient to heat the flare loop to temperatures in which it emits SXR closely following the GOES 1-8 A light curve. We also analyze the number of non-thermal electrons, the low-energy cutoff, electron spectral indices, and the changes of these parameters with time.

• OSTI ID: 21378289
• Journal Information: Astrophysical Journal (Online), Journal Name: Astrophysical Journal (Online) Journal Issue: 2 Vol. 705; ISSN 1538-4357
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BEAMS
ELECTROMAGNETIC RADIATION
ELECTRON BEAMS
ELECTRONS
ELEMENTARY PARTICLES
EMISSION
FERMIONS
GAMMA RADIATION
GOES SATELLITES
HARD X RADIATION
HEATING
HYDRODYNAMIC MODEL
IONIZING RADIATIONS
LEPTON BEAMS
LEPTONS
MAIN SEQUENCE STARS
MATHEMATICAL MODELS
PARTICLE BEAMS
PARTICLE MODELS
PLASMA HEATING
RADIATIONS
SATELLITES
SOFT X RADIATION
SOLAR ACTIVITY
SOLAR FLARES
STARS
STATISTICAL MODELS
STELLAR ACTIVITY
STELLAR FLARES
SUN
THERMODYNAMIC MODEL
VISIBLE RADIATION
X RADIATION