Solar Energetic Particles

Solar energetic particles (SEPs) are atoms that are associated with solar flares. SEPs are a type of cosmic ray. They move away from the Sun due to plasma heating, acceleration, and numerous other forces. Flares frequently inject large amounts of energetic nuclei into space, and the composition varies from flare to flare. The mechanisms involved in producing a solar flare can be better understood by studying the composition and charge of these particles. On the scale of cosmic radiation, SEPs have relatively low energies.

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February 28, 2012: Longitudinal dependence of peak intensities in solar energetic particle events -- ACE News
July 11, 2011: Modeling solar energetic particles using ACE and STEREO observations of the April 3, 2010 event -- ACE News
June 13, 2011: Multi-spacecraft observations of an energetic electron event from 0.3 to 1.0 AU -- ACE News
December 30, 2010: Broad longitudinal spread of 3He from impulsive solar energetic particle events -- ACE News
April 19, 2010: Spatial offsets of interplanetary ion and electron source regions -- ACE News
November 11, 2009: Ionic charge state distributions as a diagnostic of diverse SEP sources -- ACE News
October 8, 2009: ³He-rich solar energetic particle events from the nearly quiet Sun in 2007-08 -- ACE News
September 21, 2009: Reservoirs of near-relativistic electrons in the inner heliosphere: ACE and Ulysses observations -- ACE News
April 25, 2009: Space missions to visit the Sun -- UK Telegraph
February 23, 2009: Fractionation and ionic charge states in ³He-rich solar particle events -- ACE News
January 30, 2009: Solar physics spacecraft launched by Russia -- Spaceflight Now
November 4, 2008: "Star Trek" shield may protect astronauts -- National Geographic
November 4, 2008: May the force (field) be with you -- Scientific American
October 28, 2008: Highly-ionized Fe found at low energies in solar energetic particles: Acceleration of hot material? -- ACE News
September 26, 2008: Solar injection histories of near-relativistic solar electrons -- ACE News
April 15, 2008: Space radiation may cause prolonged cellular damage to astronauts -- Eurekalert
December 13, 2007: Earth's protective magnetic field -- Astronomy.com
October 31, 2007: The origin of energetic 3He in the inner heliosphere -- ACE News
August 31, 2007: Celebrating 10 years of ACE in space -- ACE News
August 27, 2007: Flares from Sun's far side may affect space weather of inner planets -- Science Daily
July 25, 2007: Energy-dependent charge states in impulsive solar particle evernts: A clue to the source location and conditions -- ACE News
March 29, 2007: Elemental abundances of low-energy heavy ions in large solar energetic particle events of cycle 23 -- ACE News
February 21, 2007: Space radiation hazards and the vision for space exploration: a report on the October 2005 Wintergreen conference -- AGU Space Weather
December 29, 2006: STEREO joins ACE to witness the last (?) large SEP events of cycle 23 -- ACE News
November 22, 2006: Genesis findings solve Apollo lunar soil mystery -- MoonDaily
October 3, 2006: Details of solar particles penetrating the Earth's environment revealed -- European Space Agency
August 4, 2006: Charge states reveal multiple sources in large solar energetic particle events -- ACE News
April 4, 2006: Coronal holes, jets, and the origin of 3He-rich solar energetic particle events -- ACE News
September 28, 2005: Ultraheavy elements in solar particles with >10 MeV/nucleon -- ACE News
July 8, 2005: Evidence for preferential mass per charge dependent acceleration prior to stripping in impulsive events -- ACE News
March 3, 2005: NASA study suggests giant space clouds iced Earth -- NASA HQ
February 23, 2005: Space weather aspects of the January 20, 2005 solar energetic particle event -- ACE News
November 19, 2004: Repelling cosmic rays with magnetic bubbles -- New Scientist
June 5, 2004: Sources of solar hazards in interplanetary space -- Spaceflight Now
May 24, 2004: The abundances of heavy and ultra-heavy ions in 3He-rich solar flares -- ACE News
April 27, 2004: Surprisingly low and energy-dependent charge states in impulsive solar energetic particle events -- ACE News
January 2, 2004: Upper limit on 3He fluence in solar energetic particle events -- ACE News
November 4, 2003: PoSAT-1 cosmic ray experiment monitors massive solar particle event -- SpaceDaily
October 31, 2003: Very low-energy solar electron bursts and solar wind structure -- ACE News
June 10, 2003: Correlation of solar particle onsets with the 3He/4He ratio -- ACE News
April 9, 2003: Swimming to the Sun -- NASA GSFC
March 19, 2003: Radiation dangers for Mars astronauts downgraded -- Sky & Telescope
January 8, 2003: Solar spitwads -- Science@NASA
December 13, 2002: What carries more kinetic energy than a Randy Johnson fastball, yet is only the size of an atom? -- NASA GSFC Science Question of the Week
November 18, 2002: First 3-D magnetic reconnection measurements -- SpaceDaily
June 5, 2002: Solar eruptions that miss can still hit -- NASA GSFC
May 23, 2002: A new heavy ion abundance enrichment pattern in ³He-rich solar particle events -- ACE News
April 16, 2002: Spectral variability in large solar energetic particle events -- ACE News
February 15, 2002: Composition variations at low energies during large SEP events -- ACE News
December 6: 2001: November 2001 features two of the largest solar particle events of Solar Cycle 23 -- ACE News
October 30, 2001: Plucky IMP completes 28-year observing marathon -- NASA HQ
August 7, 2001: No escaping charged particles during solar maximum -- UniSci
August 6, 2001: Ulysses spacecraft observes surprising reach of solar activity -- SpaceDaily
June 30, 2000: Energetic electrons in 3He-enhanced solar energetic particle events -- ACE News
March 17, 2000: Forecasting shock-accelerated energetic particles with ACE -- ACE News
July 30, 1999: Variability of 22Ne/20Ne at 1 MeV/nucleon measured by ACE/ULEIS -- ACE News
July 7, 1999: Charge state variations between impulsive and CME related solar energetic particle events -- ACE News
June 28, 1999: Possible connection between solar supergranulation and temporal variations of solar energetic particles -- ACE News
December 6, 1998: Ionic charge states in 3He-rich solar energetic particle events -- ACE News
September 30, 1998: Variations in the ²²Ne/²⁰Ne ratio in solar energetic particles -- ACE News