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CME and Particle Storm of July 14, 2000 |
On 14 July 2000, a full halo coronal mass ejection (CME) was recorded by SOHO's LASCO/C2 coronagraph. Halo events are CMEs aimed toward (or away from) the Earth. As they loom larger and larger they appear to envelop the Sun, forming a halo around our star.
Just prior to this, an X-class solar flare had been recorded near the center of the solar disk by the spacecraft's Extreme-ultraviolet Imaging Telescope (EIT), observing the Sun in Fe XII at 195 Angstroms. In other words, the halo event was heading for Earth.
We have collected some of the images and movies from this spectacular event, including "observations" of the torrent of energetic particles that arrived about half an hour later. Such particle storms cause snow on the images as the cameras' electronic detectors are bombarded with high-energy particles.
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LASCO/C3 |
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The MeV electron and proton fluxes as measured by the COSTEP instrument onboard SOHO. The first high energy electrons were detected at 10:38 UT. The long lasting intensity-time profiles are characteristic for fast interplanetary shocks associated with halo CMEs propagating towards Earth. Time resolution of the measurements shown is one minute. Note the particle intensity decreases on July 15/16 when the CME passed over SOHO:
The flux of solar protons measured in SOHO/ERNE following the solar eruption on July 14, 2000. The histograms represent the proton fluxes in four energy channels (3.3-6.4, 6.4-13, 13-26 and 26-51 MeV). The first protons in the highest energy channel were detected at 10:55 UT. The maximum event fluxes are more than 1,000,0000 fold compared to the constant background flux from the Milky Way:
The solar wind proton speed registered by the CELIAS/PM sensor on SOHO during the time of passage of the shock wave driven by the CME. The speed after the shock is about twice the typical solar wind speed. Relatively large uncertainties are caused by the exceptionally high background produced by energetic flare particles:
LASCO/C2 |
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LASCO/C3 |
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