LONGITUDINAL PROPERTIES OF A WIDESPREAD SOLAR ENERGETIC PARTICLE EVENT ON 2014 FEBRUARY 25: EVOLUTION OF THE ASSOCIATED CME SHOCK

: Lario D, Kwon RY, Vourlidas A, Raouafi NE, Haggerty DK, Ho GC, Anderson BJ, Papaioannou A, Gomez-Herrero R, Dresing N, Riley P

Publisher: IOP PUBLISHING LTD

: 2016

: Astrophysical Journal

: ASTROPHYSICAL JOURNAL

: ASTROPHYS J

: ARTN 72

: 819

: 1

: 23

: 0004-637X

DOI: https://doi.org/10.3847/0004-637X/819/1/72

We investigate the solar phenomena associated with the origin of the solar energetic particle (SEP) event observed on 2014 February 25 by a number of spacecraft distributed in the inner heliosphere over a broad range of heliolongitudes. These include spacecraft located near Earth; the twin Solar TErrestrial RElations Observatory spacecraft, STEREO-A and STEREO-B, located at similar to 1 au from the Sun 153 degrees west and 160 degrees east of Earth, respectively; the MErcury Surface Space ENvironment GEochemistry and Ranging mission (at 0.40 au and 31 degrees west of Earth); and the Juno spacecraft (at 2.11 au and 48 east of Earth). Although the footpoints of the field lines nominally connecting the Sun with STEREO-A, STEREO-B and near-Earth spacecraft were quite distant from each other, an intense high-energy SEP event with Fe-rich prompt components was observed at these three locations. The extent of the extreme-ultraviolet wave associated with the solar eruption generating the SEP event was very limited in longitude. However, the white-light shock accompanying the associated coronal mass ejection extended over a broad range of longitudes. As the shock propagated into interplanetary space it extended over at least similar to 190 degrees in longitude. The release of the SEPs observed at different longitudes occurred when the portion of the shock magnetically connected to each spacecraft was already at relatively high altitudes (greater than or similar to 2 R above the solar surface). The expansion of the shock in the extended corona, as opposite to near the solar surface, determined the SEP injection and SEP intensity-time profiles at different longitudes.