2008/12/01 by Claire L. Raftery, C. L. Raftery, Peter T. Gallagher +5 · 65 citations
Earth and Planetary Sciences · Physics and Astronomy · #Chromosphere #Earthquake Detection and Analysis #Evaporation #Flare #Ionosphere and magnetosphere dynamics #Plasma #Radiative cooling #Radiative transfer #Solar and Space Plasma Dynamics #Solar flare #Thermal conduction #astro-ph
paper · pdf · doi:10.1051/0004-6361:200810437
published in Astronomy and Astrophysics 494(3), 1127-1136 (EDP Sciences) · 10 pages, 7 figures, 2 tables. Accepted for publication in A&A
arxiv created 2008/12/01 · openalex publication_date 2008/12/11 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
<i>Aims. <i/>We investigate the temporal evolution of temperature, emission measure, energy loss, and velocity in a C-class solar flare from both observational and theoretical perspectives. <i>Methods. <i/>The properties of the flare were derived by following the systematic cooling of the plasma through the response functions of a number of instruments – the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI; >5 MK), GOES-12 (5–30 MK), the Transition Region and Coronal Explorer (TRACE 171 Å; 1 MK), and the Coronal Diagnostic Spectrometer (CDS; ~0.03–8 MK). These measurements were studied in combination with simulations from the 0-D enthalpy based thermal evolution of loops (EBTEL) model. <i>Results. <i/> At the flare onset, upflows of ~90 km s<sup>-1<sup/> and low-level emission were observed in , consistent with pre-flare heating and gentle chromospheric evaporation. During the impulsive phase, upflows of ~80 km s<sup>-1<sup/> in and simultaneous downflows of ~20 km s<sup>-1<sup/> in and were observed, indicating explosive chromospheric evaporation. The plasma was subsequently found to reach a peak temperature of 13 MK in approximately 10 min. Using EBTEL, conduction was found to be the dominant loss mechanism during the initial ~300 s of the decay phase. It was also found to be responsible for driving gentle chromospheric evaporation during this period. As the temperature fell below ~8 MK, and for the next ~4000 s, radiative losses were determined to dominate over conductive losses. The radiative loss phase was accompanied by significant downflows of <i>≤<i/>40 km s<sup>-1<sup/> in . <i>Conclusions. <i/> This is the first extensive study of the evolution of a canonical solar flare using both spectroscopic and broad-band instruments in conjunction with a 0-D hydrodynamic model. While our results are in broad agreement with the standard flare model, the simulations suggest that both conductive and non-thermal beam heating play important roles in heating the flare plasma during the impulsive phase of at least this event.