Different Power-law Indices in the Frequency Distributions of Flares with and without Coronal Mass Ejections

2006/09/07 by S. Yashiro, S. Akiyama, N. Gopalswamy +1 · 2 citations
Physics and Astronomy · #astro-ph

paper · pdf · doi:10.1086/508876

published as Astrophys.J.650:L143-L146,2006 · 4 pages, 2 figures embedded, accepted for publication in ApJL

arxiv created 2006/09/07 · arxiv updated 2011/02/11

Abstract

We investigated the frequency distributions of flares with and without coronal mass ejections (CMEs) as a function of flare parameters (peak flux, fluence, and duration of soft X-ray flares). We used CMEs observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission and soft X-ray flares (C3.2 and above) observed by the GOES satellites during 1996 to 2005. We found that the distributions obey a power-law of the form: dN/dX~X^-alpha, where X is a flare parameter and dN is the number of events recorded within the interval [X, X+dX]. For the flares with (without) CMEs, we obtained the power-law index alpha=1.98+-0.05 (alpha=2.52+-0.03) for the peak flux, alpha=1.79+-0.05 (alpha=2.47+-0.11) for the fluence, and alpha=2.49+-0.11 (alpha=3.22+-0.15) for the duration. The power-law indices for flares without CMEs are steeper than those for flares with CMEs. The larger power-law index for flares without CMEs supports the possibility that nanoflares contribute to coronal heating.

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