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Coronal mass ejections
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Space Weather Model Simulates Solar Storms From Nowhere

Our ever-changing sun continuously shoots solar material into space. The grandest such events are massive clouds that erupt from the sun, called coronal mass ejections, or CMEs. These solar storms often come first with some kind of warning - the bright flash of a flare, a burst of heat or a flurry of solar energetic particles. But another kind of storm has puzzled scientists for its lack of typical warning signs: They seem to come from nowhere, and scientists call them stealth CMEs.
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Magnetic flux ropes
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Title: Direct Evidence of an Eruptive, Filament-Hosting Magnetic Flux Rope Leading to a Fast Solar Coronal Mass Ejection
Author: Bin Chen, Timothy S. Bastian, Dale E. Gary

Magnetic flux ropes (MFRs) are believed to be at the heart of solar coronal mass ejections (CMEs). A well-known example is the prominence cavity in the low corona that sometimes makes up a three-part white-light CME upon its eruption. Such a system, which is usually observed in quiet-Sun regions, has long been suggested to be the manifestation of an MFR with relatively cool filament material collecting near its bottom. However, observational evidence of eruptive, filament-hosting MFR systems has been elusive for those originating in active regions. By utilizing multi-passband extreme-ultra-violet (EUV) observations from SDO/AIA, we present direct evidence of an eruptive MFR in the low corona that exhibits a hot envelope and a cooler core; the latter is likely the upper part of a filament that undergoes a partial eruption, which is later observed in the upper corona as the coiled kernel of a fast, white-light CME. This MFR-like structure exists more than one hour prior to its eruption, and displays successive stages of dynamical evolution, in which both ideal and non-ideal physical processes may be involved. The timing of the MFR kinematics is found to be well correlated with the energy release of the associated long-duration C1.9 flare. We suggest that the long-duration flare is the result of prolonged energy release associated with the vertical current sheet induced by the erupting MFR.

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RE: Coronal mass ejection
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UNH Scientists: Sun Delivered Curveball of Powerful Radiation at Earth

A potent follow-up solar flare, which occurred Friday (Jan. 17, 2012), just days after the Sun launched the biggest coronal mass ejection (CME) seen in nearly a decade, delivered a powerful radiation punch to Earths magnetic field despite the fact that it was aimed away from our planet.
According to University of New Hampshire scientists currently studying and modelling various aspects of solar radiation, this was due to both the existing population of energetic particles launched by the first CME and a powerful magnetic connection that reeled particles in towards Earth from the Suns blast region, which had spun to an oblique angle.

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SwRI-led RAD measures radiation from solar storm

The largest solar particle event since 2005 hit the Earth, Mars and the Mars Science Laboratory spacecraft travelling in-between, allowing the onboard Radiation Assessment Detector to measure the radiation a human astronaut could be exposed to en route to the Red Planet.
On Sunday, a huge coronal mass ejection erupted from the surface of the sun, spewing a cloud of charged particles in our direction, causing a strong "S3" solar storm. A NASA Goddard Space Weather Lab animation of the CME illustrates how the disturbance impacts Earth, Mars and several spacecraft. Solar storms can affect the Earth's aurorae, satellites, air travel and GPS systems; no harmful effects to the Mars Science Laboratory have been detected from this solar event.

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Stereo vista
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NASA Spacecraft Track Solar Storms From Sun To Earth



'NASA's STEREO spacecraft and new data processing techniques have succeeded in tracking space weather events from their origin in the Sun's ultrahot corona to impact with the Earth 96 million miles away, resolving a 40-year mystery about the structure of the structures that cause space weather: how the structures that impact the Earth relate to the corresponding structures in the solar corona.
Despite many instruments that monitor the Sun and a fleet of near-earth probes, the connection between near-Earth disturbances and their counterparts on the Sun has been obscure, because CMEs and the solar wind evolve and change during the 96,000,000 mile journey from the Sun to the Earth.
STEREO includes "heliospheric imager" cameras that monitor the sky at large angles from the Sun, but the starfield and galaxy are 1,000 times brighter than the faint rays of sunlight reflected by free-floating electron clouds inside CMEs and the solar wind; this has made direct imaging of these important structures difficult or impossible, and limited understanding of the connection between space storms and the coronal structures that cause them.
Newly released imagery reveals absolute brightness of detailed features in a large geoeffective CME in late 2008, connecting the original magnetized structure in the Sun's corona to the intricate anatomy of an interplanetary storm as it impacted the Earth three days later. At the time the data were collected, in late 2008, STEREO-A was nearly 45 degrees ahead of the Earth in its orbit, affording a very clear view of the Earth-Sun line.'



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Coronal mass ejection
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New images reveal never-before-seen structures of the solar wind as it travels toward and impacts Earth

Using data collected by NASA's STEREO spacecraft, researchers at Southwest Research Institute and the National Solar Observatory have developed the first detailed images of solar wind structures as plasma and other particles from a coronal mass ejection (CME) travelled 93 million miles and impacted Earth.
The images from a December 2008 CME event reveal an array of dynamic interactions as the solar wind, traveling at speeds up to a million miles per hour, shifts and changes on its three-day journey to Earth, guided by the magnetic field lines that spiral out from the Sun's surface. Observed structures include the solar wind piling up at the leading edge of a CME, voids in the interior, long thread-like structures, and rear cusps. Quiet periods show a magnetic disconnection phenomenon called a plasmoid, "puffs" that correlate with in-situ density fluctuations, and V-shaped structures centred on the current sheet - a heliospheric structure in which the polarity of the Sun's magnetic field changes from north to south.

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