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Title: MAGNETIC FIELD-LINE LENGTHS IN INTERPLANETARY CORONAL MASS EJECTIONS INFERRED FROM ENERGETIC ELECTRON EVENTS

Abstract

About one quarter of the observed interplanetary coronal mass ejections (ICMEs) are characterized by enhanced magnetic fields that smoothly rotate in direction over timescales of about 10-50 hr. These ICMEs have the appearance of magnetic flux ropes and are known as 'magnetic clouds' (MCs). The total lengths of MC field lines can be determined using solar energetic particles of known speeds when the solar release times and the 1 AU onset times of the particles are known. A recent examination of about 30 near-relativistic (NR) electron events in and near 8 MCs showed no obvious indication that the field-line lengths were longest near the MC boundaries and shortest at the MC axes or outside the MCs, contrary to the expectations for a flux rope. Here we use the impulsive beamed NR electron events observed with the Electron Proton and Alpha Monitor instrument on the Advanced Composition Explorer spacecraft and type III radio bursts observed on the Wind spacecraft to determine the field-line lengths inside ICMEs included in the catalog of Richardson and Cane. In particular, we extend this technique to ICMEs that are not MCs and compare the field-line lengths inside MCs and non-MC ICMEs with those in the ambientmore » solar wind outside the ICMEs. No significant differences of field-line lengths are found among MCs, ICMEs, and the ambient solar wind. The estimated number of ICME field-line turns is generally smaller than those deduced for flux-rope model fits to MCs. We also find cases in which the electron injections occur in solar active regions (ARs) distant from the source ARs of the ICMEs, supporting CME models that require extensive coronal magnetic reconnection with surrounding fields. The field-line lengths are found to be statistically longer for the NR electron events classified as ramps and interpreted as shock injections somewhat delayed from the type III bursts. The path lengths of the remaining spike and pulse electron events are compared with model calculations of solar wind field-line lengths resulting from turbulence and found to be in good agreement.« less

Authors:
 [1];  [2];  [3]
  1. Air Force Research Laboratory, RVBXS, 29 Randolph Rd, Hanscom AFB, MA 01731 (United States)
  2. Johns Hopkins University, Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States)
  3. Code 661, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
Publication Date:
OSTI Identifier:
21578263
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 736; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/736/2/106; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; INTERPLANETARY SPACE; MAGNETIC FIELDS; MAGNETIC FLUX; MASS; MATTER; SOLAR CORONA; SOLAR ELECTRONS; SOLAR WIND; TAIL ELECTRONS; ATMOSPHERES; ELECTRONS; ELEMENTARY PARTICLES; FERMIONS; LEPTONS; RADIATIONS; SOLAR ACTIVITY; SOLAR ATMOSPHERE; SOLAR PARTICLES; SOLAR RADIATION; SPACE; STELLAR ACTIVITY; STELLAR ATMOSPHERES; STELLAR CORONAE; STELLAR RADIATION; STELLAR WINDS

Citation Formats

Kahler, S. W., Haggerty, D. K., and Richardson, I. G., E-mail: AFRL.RVB.PA@hanscom.af.mil. MAGNETIC FIELD-LINE LENGTHS IN INTERPLANETARY CORONAL MASS EJECTIONS INFERRED FROM ENERGETIC ELECTRON EVENTS. United States: N. p., 2011. Web. doi:10.1088/0004-637X/736/2/106.
Kahler, S. W., Haggerty, D. K., & Richardson, I. G., E-mail: AFRL.RVB.PA@hanscom.af.mil. MAGNETIC FIELD-LINE LENGTHS IN INTERPLANETARY CORONAL MASS EJECTIONS INFERRED FROM ENERGETIC ELECTRON EVENTS. United States. doi:10.1088/0004-637X/736/2/106.
Kahler, S. W., Haggerty, D. K., and Richardson, I. G., E-mail: AFRL.RVB.PA@hanscom.af.mil. Mon . "MAGNETIC FIELD-LINE LENGTHS IN INTERPLANETARY CORONAL MASS EJECTIONS INFERRED FROM ENERGETIC ELECTRON EVENTS". United States. doi:10.1088/0004-637X/736/2/106.
@article{osti_21578263,
title = {MAGNETIC FIELD-LINE LENGTHS IN INTERPLANETARY CORONAL MASS EJECTIONS INFERRED FROM ENERGETIC ELECTRON EVENTS},
author = {Kahler, S. W. and Haggerty, D. K. and Richardson, I. G., E-mail: AFRL.RVB.PA@hanscom.af.mil},
abstractNote = {About one quarter of the observed interplanetary coronal mass ejections (ICMEs) are characterized by enhanced magnetic fields that smoothly rotate in direction over timescales of about 10-50 hr. These ICMEs have the appearance of magnetic flux ropes and are known as 'magnetic clouds' (MCs). The total lengths of MC field lines can be determined using solar energetic particles of known speeds when the solar release times and the 1 AU onset times of the particles are known. A recent examination of about 30 near-relativistic (NR) electron events in and near 8 MCs showed no obvious indication that the field-line lengths were longest near the MC boundaries and shortest at the MC axes or outside the MCs, contrary to the expectations for a flux rope. Here we use the impulsive beamed NR electron events observed with the Electron Proton and Alpha Monitor instrument on the Advanced Composition Explorer spacecraft and type III radio bursts observed on the Wind spacecraft to determine the field-line lengths inside ICMEs included in the catalog of Richardson and Cane. In particular, we extend this technique to ICMEs that are not MCs and compare the field-line lengths inside MCs and non-MC ICMEs with those in the ambient solar wind outside the ICMEs. No significant differences of field-line lengths are found among MCs, ICMEs, and the ambient solar wind. The estimated number of ICME field-line turns is generally smaller than those deduced for flux-rope model fits to MCs. We also find cases in which the electron injections occur in solar active regions (ARs) distant from the source ARs of the ICMEs, supporting CME models that require extensive coronal magnetic reconnection with surrounding fields. The field-line lengths are found to be statistically longer for the NR electron events classified as ramps and interpreted as shock injections somewhat delayed from the type III bursts. The path lengths of the remaining spike and pulse electron events are compared with model calculations of solar wind field-line lengths resulting from turbulence and found to be in good agreement.},
doi = {10.1088/0004-637X/736/2/106},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 736,
place = {United States},
year = {2011},
month = {8}
}