A Comparison of Solar X-Ray Flare Timescales and Peak Temperatures with Associated Coronal Mass Ejections

Abstract

Recent work has shown that plots of solar flare X-ray peak temperatures, Tm, versus log peak fluxes, Fp, show statistically significant separations of lower Tm flares with fast (Vcme ≥ 1000 km s−1) and wide (Wcme = 360°) strong coronal mass ejections (CMEs) from higher Tm flares with no CMEs or slow (Vcme < 1000 km s−1) or narrow (<360°) weak CMEs. We extend that statistical separation to CME kinetic energies, Ecme. Flares with long-duration timescales also have well-known associations with fast CMEs and solar energetic (E > 10 MeV) particle events. Using a data set of 585 ≥ M3.0 GOES X-ray flares, we ask whether longer flare timescales (rise times, TR; durations from onset to half-power decay, TD; decay times to half power, Td; and decay times to C2, TC2) also statistically discriminate among the three groups of CMEs for speeds, widths, and energies. All log–log plots of flare timescales versus Fp produce significant separations of the three groups of CMEs generally better than those of Tm versus log Fp. We use separations of CME distribution medians to sort the four flare timescales as effective discriminants among the three CME groups. Separations between the confined flares (no-CMEs) and weak CMEs are generally smaller than those between the weak CMEs and strong CMEs. A combination of Tm and TC2 provides optimum group separations, but Tm and log TD or log Td appears best for CME forecasting purposes.